www.elsevier.com/locate/sedgeo

Sedimentary Geology 1

Palaeohydrology and sedimentary impacts of jfkulhlaups fromKverkfjfll, Iceland

Jonathan L. Carrivicka,*, Andrew J. Russelld, Fiona S. Tweedb, Dave Twiggc

aSchool of Earth Sciences and Geography, Keele University, Staffordshire, ST5 5BG, United KingdombDepartment of Geography, Staffordshire University, College Road, Stoke-on-Trent, Staffordshire, ST4 2DE, United Kingdom

cDepartment of Civil and Building Engineering, Loughborough University, Leicestershire, LE11 3TU, United KingdomdSchool of Politics and Sociology University of Newcastle, Daysh Building, Newcastle Upon Tyne, NE1 7RU, UK

Received 6 January 2004; received in revised form 1 July 2004; accepted 20 July 2004

Abstract

Jfkulhlaups (glacial outburst floods) occur frequently within Iceland and within most glaciated regions of the world. The

largest jfkulhlaups known to have occurred within Iceland drained from the northern margin of the Vatnajfkull and along the

Jfkulsa a Fjfllum during the Holocene. However, little is known about the number, age and flow characteristics of the Jfkulsa aFjfllum jfkulhlaups. One source of meltwater into the Jfkulsa a Fjfllum is Kverkfjfll, a glaciated stratovolcano. This paper

provides detailed sedimentological evidence demonstrating that jfkulhlaups have routed through Kverkfjallarani and hence

from Kverkfjfll. Sedimentological evidence of jfkulhlaups includes valley-fill deposits and slack water deposits. Lithofacies,

which are indicative of high-magnitude fluvial sedimentation, show that these deposits cannot be the result of nonjfkulhlaupprocesses. The situation and nature of the sediments permit palaeoflow reconstructions. Fine-grained deposits within slack

water deposits mark a break in jfkulhlaup deposition and suggest that at least three jfkulhlaups have drained through

Hraundalur, the predominant valley within Kverkfjallarani. Evidence of lava overrunning dwetT jfkulhlaup deposits indicates

that jfkulhlaups occurred in close association with volcanic eruptions in the Biskupsfell fissure. The largest jfkulhlaup was

initially hyperconcentrated and subsequently became more fluid. Slope–area reconstructions indicate that the largest jfkulhlauphad a probable average peak discharge of 45,000–50,000 m3 s�1; however, the peak discharge attenuated by 25–30% in just 25

km. These observations quantify the number, rheology, hydraulics and chronology of jfkulhlaups from Kverkfjfll and hence

within the Jfkulsa a Fjfllum. This study presents a model of jfkulhlaup impacts and characteristics from glaciated volcanoes

and/or within volcanic rifting zones.

D 2004 Elsevier B.V. All rights reserved.

Keywords: Kverkfjfll; Outburst floods; Jfkulhlaups; Rheology; Flow characteristics; Iceland

1. Introduction, background and rationale

0037-0738/$ - see front matter D 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.sedgeo.2004.07.005

* Corresponding author. Tel.: +44 1782 583620; fax: +44 1782

715261.

E-mail address: j.l.carrivick@keele.ac.uk (J.L. Carrivick).

Jfkulhlaups (glacial outburst floods) occur fre-

quently within Iceland and indeed within most

72 (2004) 19–40

Fig. 1. The location of Kverkfjfll within Iceland. Inset boxes locate

other diagrams within this study. Arrows denote palaeoflow

directions based on Carrivick et al. (in press).

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4020

glaciated regions of the world (e.g., Haerberli, 1983;

Bjornsson, 1992; Tomasson, 2002). Large jfkulhlaupshave the capacity to cause loss of life and damage to

infrastructure, communications and managed land

(see Costa and Schuster, 1988 and Tomasson, 2002

for further references). These effects of jfkulhlaupsare related most generally to the volume, propagation

and deposition of water and sediment across a

landscape. However, the precise nature of a

jfkulhlaup sedimentary impact depends upon inter-

actions between the jfkulhlaup flow and the

jfkulhlaup routeway (Maizels and Russell, 1992).

Sedimentary landforms attributed to jfkulhlaups,including dunes, bars and terraces, have been

described, interpreted and classified (e.g., Carling,

1996; Russell and Marren, 1999; Carling et al., 2002).

This has allowed models of jfkulhlaup flow dynam-

ics, flow rheology and the control of jfkulhlaupmagnitude and frequency upon outwash fan or sandar

evolution to be proposed (Maizels, 1989, 1991, 1993,

1995, 1997). However, these models remain to be

tested for jfkulhlaups within confined, steep, bedrock

channel systems.

The largest jfkulhlaups known to have occurred in

Iceland drained along the Jfkulsa a Fjfllum within the

Northern Volcanic Zone (NVZ) (Thorarinsson, 1950;

Saemundsson, 1973; Tomasson, 1973; 2002; Fig. 1).

These jfkulhlaups routed along bedrock channels.

The inland area of the NVZ is both a semiarid desert

and an active volcanic rifting zone. Consequently, the

NE of Iceland has high denudation rates, high

sediment availability and frequent tectonic and vol-

canic activity (Kayhko et al., 2002; Olafsdottir and

Guðmundsson, 2002).

Controversy surrounds the number, age and flow

characteristics of the Jfkulsa a Fjfllum jfkulhlaups.Previous research concerning the number and age of

the Jfkulsa a Fjfllum jfkulhlaups has concentrated on

the generally accessible northern reaches of the

Jfkulsa a Fjfllum (Thorarinsson, 1950; Saemundsson,

1973; Tomasson, 1973). Tephra found between soil

horizons within and outside jfkulhlaup canyons

suggests that there has been more than one erosive

jfkulhlaup during the Holocene (Tomasson, 1973;

Eliasson, 1977; Waitt, 2002). However, there is

considerable discrepancy between authors who have

proposed that two (Saemundsson, 1973; Waitt, 1998),

three (Waitt, 2002) and even four (Helgason, 1987)

canyon-forming jfkulhlaups have occurred along the

Jfkulsa a Fjfllum during the Holocene. Many smaller

dhistoricT jfkulhlaups have also occurred along the

Jfkulsa a Fjfllum (Thorarinsson, 1950) but have not

overtopped canyon rims.

The literature also fails to determine a precise

source of the Jfkulsa a Fjfllum jfkulhlaups. Large

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 21

(erosive) Jfkulsa a Fjfllum jfkulhlaups may have

originated within the BarWabunga caldera beneath

Vatnajfkull, because jfkulhlaup impacts can be traced

to form routeways that emanate from the Dyng-

jujfkull margin (Tomasson, 1973). Waitt (2002)

concluded that the Kverkfjfll volcano was also a

source of jfkulhlaup flows but suggested that these

flows were unlikely to have been of the capacity to

form canyons. Carrivick et al. (in press) support

Waitt’s (2002) suggestion and presented convincing

evidence of landforms within a network of anasto-

mosing routeways to show that at least two

jfkulhlaups have routed from Kverkfjfll. There are

therefore at least two separate sources of Jfkulsa a

Fjfllum jfkulhlaups.The rheology of Jfkulsa a Fjfllum jfkulhlaups has

received only minor attention from researchers.

Massive, poorly sorted and upwardly coarsening

sediments within the vicinity of Asbyrgi have been

interpreted to be the product of high-magnitude

sediment-rich jfkulhlaups (Knudsen and Russell,

2001). Carrivick et al. (in press) also suggest sedi-

ment-rich fluidal flows; a rheology inferred from

superficial bars, terraces, alluvial fans and erratic

boulders within the Kverkfjfll proglacial zone. How-ever, besides these two studies, there have been no

other detailed observations and measurements of the

sedimentological impacts of the Jfkulsa a Fjfllumjfkulhlaups specifically or of jfkulhlaups within

volcanic rifting zones more generally.

2. Aims

The aims of this paper are firstly to reconstruct

the characteristics of the largest jfkulhlaup from

Kverkfjfll that routed along Hraundalur. Secondly,

we compare this model of a jfkulhlaup within an

active volcanic rifting zone to existing models of

jfkulhlaup characteristics.

3. Study site

Kverkfjfll is a glaciated stratovolcano and is a part

of the Kverkfjfll Volcanic System (KVS; Johannesson

and Saemundsson, 1989; Fig. 1). The southerly

component of the KVS is heavily glaciated and

comprises two subglacial calderas, supraglacial caul-

drons and a subglacial lake (Bjornsson, 1988, 2002;

Bjornsson and Einarrson, 1991). Both calderas are 5–

7 km in diameter and at an elevation of approximately

1600 m. The glacier Kverkjfkull breaches the rim of

the most northerly of these calderas and descends to

approximately 900 m within 6 km. The proglacial area

of the KVS is known as Kverkfjallarani and is

dominated by a series of parallel volcanic pillow–

hyaloclastite ridges, each typically 100 m high and

several kilometres long (Johannesson and Saemunds-

son, 1989). These ridges mark fissures that probably

erupted beneath the Late Devensian ice sheet (Karhu-

nen, 1988). The Late Devensian ice sheet had receded

from north-central Iceland by ~12,000 BP

(GuWmundsson, 1997). Between the present day

pillow–hyaloclastite ridges, postglacial subaerial lava

flows tend to fill valley floors (Karhunen, 1988).

Much of the sedimentological evidence of jfkulhlaupsthrough Kverkfjallarani overlies postglacial lava flows

and is located either in areas of valley expansion,

tributary valley mouths or behind downslope protru-

sions of pillow–hyaloclastite ridges. This study

concentrates upon data from within and around

Hraundalur (dlava valleyT), which stretches 20 km

northwards from Kverkjfkull proglacial moraine

limits to the Krepputungahraun (dKrepputunga lavaT;Fig. 1). Hraundalur is thus the largest valley within

Kverkfjallarani. For note, names of geomorphological

features are those used by Guttormson (1987), who

compiled official and unofficial names from several

other academic and nonacademic sources.

4. Methodology

A set of key criteria was adapted from Marren

(2000) (Table 1) to distinguish sediments that are the

product of jfkulhlaups from those that are the product

of other processes. This research uses the spatial

distribution of these jfkulhlaup sediments to define

jfkulhlaup routeways. The Interpretation of sediment

facies and architecture is used to determine jfkulhlaupflow characteristics. Extensive fieldwork was under-

taken during the summers of 2000–2003. Four

profiles up to a maximum height of 7 m were

manually excavated into the faces of incised valley-

fill deposits. Seven pits were manually excavated to a

Table 1

Sedimentary key criteria indicate that sediments cannot have been deposited by low-magnitude high-frequency flows (adapted from

Marren, 2000)

Sedimentary key criteria for

falsification of the low-magnitude

high-frequency hypothesis

Sedimentary characteristics Selected references

Hyperconcentrated flow Volumes of sediment too great to be entrained

by dnormalT flows. Poor sorting, massive,

reverse grading, poor imbrication, dfloatingTclasts. Traction carpetsT

Costa (1988); Todd (1989); Sohn (1997)

Debris flow Volumes of sediment too great to be entrained

by dnormalT flows. Very poor sorting, massive.

May show correlation between maximum

particle size and bed thickness

Costa (1988); Nemec and Steel (1984)

Strongly uniform palaeoflow Indicates lack of repeated reworking by falling

stage flows

Bluck (1974)

Thick inversely graded units Inversely graded units in coarse sediment

thicker than c. 2 m. Formed on rising limb

of flood

Maizels (1993)

Large-scale gravel foresets Thick (N2 m) cross-bedded coarse gravel.

Formed in expansion or pendant bars and

in dunes

Baker (1973); Carling (1996)

Reactivation surfaces in large-scale

cross-stratified gravel

Cross-bedded gravel with low-angle

reactivation surfaces. Indicates that bar

has been subjected to repeated floods

Russell and Marren (1999)

Laterally extensive erosion surfaces Contrast with localised incision common in

low-magnitude high-frequency rivers.

Indicates initial incision of flood prior to

aggradation

Kehew (1993)

Architecture Features occurring on a valley-wide scale.

Alternatively, features indicate peak discharges

larger than expected by size of glacier

catchment area

Maizels (1995), (1997);

Miall (1977), (1985)

Obstacle marks Protruding bedrock, perched boulders and ice

blocks may become obstacles.

Downstream-fining trends

Russell (1993); Fay (2001), (2002a,b)

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4022

maximum depth of 3 m within Hraundalur tributary

valleys. Sediment texture, sorting, grade, grain mor-

phology and lithology, fabric properties and any dip or

orientation of beds and/or clasts were recorded in the

field using the established criteria suggested by Jones

et al. (1989). Additionally, several representative beds

within each pit were sampled for grain size analyses

and others for determining major-element composi-

tion. Major-element composition of some fine-grained

samples was sought in order to investigate suspicions

of tephra. Suspected tephra samples were prepared by

manufacturing them into a glass disc and then

subjecting to X-ray fluorescence (XRF).

Slope–area calculations have been widely used to

reconstruct jfkulhlaup hydraulics. Slope–area techni-

ques use measurements of maximum water stage at

several sites along a channel to calculate a cross-

sectional averaged velocity and hence discharge. It

should be noted that in this study, these calculations

pertain to the largest jfkulhlaup to have deposited

slack water sediments through Hraundalur, but

assume that bed elevation has not changed. Because

some postflood in-filling has occurred from perennial

slope processes, reconstructed peak discharges may

therefore be taken as minimum estimates. Further-

more, bed elevation was assumed to remain constant

during the flood. Slope–area calculations of palaeo-

flow velocities and discharges were computed for

cross-sections measured off a Digital Elevation Model

(DEM) of the Kverkfjallarani area. The DEM was

georeferenced from 29 ground control points that

were surveyed using a Differential Global Positioning

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 23

System (DGPS) relative to the Icelandic Geodetic

Network. The DEM was processed using digital

stereo aerial photographs and Erdas Orthomax soft-

ware. The resultant DEM has a 10-m horizontal

resolution and therefore allows accurate and high-

resolution cross-sectional areas of jfkulhlaup channelsto be computed. Combining knowledge of the

location and altitude of slack water deposits and of

other wash limit altitudes along Hraundalur, slope–

area calculations were made on 124 cross-sections. At

each cross-section, discharges were calculated from a

flow velocity based on channel gradient, roughness

and cross-sectional geometry.

5. Sediments within Kverkfjallarani

5.1. Valley-fill deposits

Valley-fill deposits are located where the Hraunda-

lur valley widens and are of a relatively low gradient

(Fig. 2). Valley-fill deposits generally span the width

and often a considerable length of Hraundalur. Valley-

fill sediments include boulders and cobble, granule

and sand facies. Isolated boulders occur in most of the

granule-dominated units. Cobble units and granule

facies are dominant throughout all of the profiles (Fig.

2). Boulders are almost exclusively subrounded

subaerial basalt lava blocks, although some are well-

rounded palagonite clasts. Palagonite is indurated

volcaniclastic and pyroclastic sediments or more

specifically a weathered and hydrated product of

basaltic sideromelene (Cas and Wright, 1988). Side-

romelene is found at the margin of pillows in pillow

lava. Cobbles and pebbles are usually subrounded and

are derived from pillow lava bricks and subaerial

basalt, scoria or pumice. Granules are heterolithic and

include a whole continuum of basalt, scoria, spatter

and pumice shards. In all profiles, sand is black and

basaltic.

Isolated boulders occur throughout profiles 1, 3

and 4 but are absent from profile 2. Individual

boulders have b-axes of up to 1 m. Cobble and

pebble units typically comprise pumice and lithic-

fragment clasts within a matrix of granules and

volcanic sands (Fig. 2). It is uncommon for cobble

and pebble units to be clast-supported, but several

matrix-poor units occur, for example, within the upper

units of profile 2 and midway up profile 4 (Fig. 2).

The vast majority of these units are therefore

structureless, with the remaining matrix-poor and

clast-supported units being upwardly coarsening.

Upward coarsening units are particularly prevalent

within the upper part of profile 2 (Fig. 2).

5.2. Tributary mouth deposits

Tributary valleys running into Hraundalur contain

distinctive suites of exotic sediments at the valley

mouth. This is the case for tributary valleys within

both ice marginally proximal and distal reaches of

Hraundalur (Figs. 3 and 4). Superficially, tributary

mouth sediments have a local gradient of either 08 ormore commonly of 18. This slight gradient is notable,because the dip is into or up the tributary valley.

Surface clasts are subangular, matrix-supported and

coarse in comparison to those within lower units. Pit 2

has occasional vegetation rootlets immediately

beneath the surface unit. Tributary mouth sediments

include granule, sand and silt facies. Isolated pebbles

occur in many of the granule-dominated units and less

frequently within sand units. Cobbles and boulders are

absent from tributary mouth sediments.

Pebble beds and pebble-dominated units are

present in all pits and predominate midway down

the excavated depth of each pit (Figs. 3 and 4). Pebble

units are supported by a matrix of heterolithic granule

and coarse black sand. With the exception of pit 5,

units beneath the pebble and granule beds are massive

coarse sands occasionally interspersed by thin (less

than 5 cm) beds of granules. Uppermost units are

highly varied between pits. Upper units in pits 1, 3

and 5 contain thin (a few centimetres) beds of

granules and sands interspersed with silty sand beds.

Upper units in pits 2, 4 and 7 contain thicker (tens of

centimetres) massive units of polymodal heterolithic

granular and/or sand-dominated material. Pit 6 fea-

tures convoluted and chaotically disturbed beds of silt

and sand. These sand beds also contain irregular

lenses of fine heterolithic openwork granules (Fig. 4).

With the exception of silt beds, all samples taken for

grain size analysis were polymodal (Figs. 3 and 4).

All pits have surface deposits of subangular pebbles

dominated by pillow lava clasts. Tributary mouth

sediments within Kverkfjallarani therefore have sev-

eral characteristics that are similar although of finer

Fig. 2. Sedimentary logs of valley-fill profiles. Inset shows location of profiles within Hraundalur. NB. For clarity vertical scale varies between profiles. Dip and orientation of beds

are given where appropriate. Bracketed numbers are b-axis measurements of the largest clasts. No attempt is made to correlate stratigraphy between profiles in order to preserve the

high spatial variability of the sediments.

J.L.Carrivick

etal./Sedimentary

Geology172(2004)19–40

24

Fig. 3. Sedimentary logs of distal slack water pits excavated within Hraundalur. Inset shows location of pits within Hraundalur. NB. Vertical scale is uniform on all logs. Dip and orientation of beds are given where appropriate. Bracketed numbers are

b-axis measurements of the largest clasts. Encircled numbers are tephra samples. Black bars on y-axes indicate a separation between jfkulhlaups, from either tephra or silt layers.

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 pp. 25–28

Fig. 4. Sedimentary logs of proximal slack water pits excavated within Hraundalur. Inset shows location of pits within Hraundalur. NB. Vertical scale is uniform on both logs. Dip and

orientation of beds are given where appropriate. Bracketed numbers are b-axis measurements of the largest clasts.

J.L.Carrivick

etal./Sedimentary

Geology172(2004)19–40

29

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4030

grade to valley-fill deposits. Finally, it is evident that

pits further from the Hraundalur valley axis contain

generally finer sediment and thinner units than those

that are closer to the valley margin (Fig. 3).

6. Interpretation

6.1. Valley-fill sediments

We interpret valley-fill sediments within Hraun-

dalur (Fig. 2) to be the product of high-magnitude

subaerial fluidal and hyperconcentrated flows. The

occurrence of laterally extensive valley-fill sedi-

ments implies widespread flood inundation. How-

ever, the variability of the valley-fill sediments

themselves preclude laterally uniform flow condi-

tions. Such laterally extensive features are typical of

dunconfinedT low stage subcritical flows (Allen,

1985) and may also suggest jfkulhlaup flows

(Marren, 2000). The variability exhibited by valley-

fill sediments indicates considerable and abrupt

alterations in flow hydraulics and/or sediment. Ero-

sional and reactivation surfaces lead to a preference

for either a multievent hypothesis or perhaps several

flow pulses (Collinson, 1970). Relatively thin sand

beds and minor textural changes and/or bimodality

within units are interpreted as falling stage reworking

of relatively featureless granular sheets (Boothroyd

and Ashley, 1975; Smith, 1974).

Valley-fill sediments represent a continuum of flow

rheologies. Structureless or massive units containing

boulders within a finer-grained and poorly sorted

matrix, as well as matrix-supported pebbles, are

products of hyperconcentrated flows (Costa, 1988).

These units are therefore indicative of jfkulhlaups inwhich rapid deposition from both tractive and

suspended deposits occurred simultaneously. Further-

more, it can further be inferred that jfkulhlaupsthrough Hraundalur comprised basal granular flows,

a rheological property suggested by Kneller and

Branney (1995) and substantiated by Manville and

White (2003) as typifying high-magnitude floods that

entrain voluminous unweathered volcaniclastic mate-

rial. However, the vertical trend from matrix-sup-

ported to clast-supported units, particularly within pit

sections, suggests transitions from hyperconcentrated

to more fluidal flows. Sorted, clast-supported and

imbricated cobble and pebble units are interpreted to

represent grain by grain deposition from traction load

within a high-energy turbulent flow (Brayshaw,

1984). Imbricated clasts are indicative of fluidal bed

load (Allen, 1985). Fluidal lithofacies may or may not

be the product of jfkulhlaups, but the calibre of

material certainly indicates a high-magnitude flow.

Horizontally bedded and poorly sorted ungraded

granules reflect deposition from a turbulent suspen-

sion prior to late-stage traction transport (Brennand,

1994). A series of units that progressively coarsen

upwards reflects rising stage fluidal deposition

(Bluck, 1974; Allen, 1985; Maizels, 1993, 1997).

However, upwardly coarsening units can be sugges-

tive of sediment-laden or hyperconcentrated

jfkulhlaups, because upwardly coarsening units can

reflect rapid deposition from flows where larger clasts

become dbouyantT with dispersive stress from grain

interactions (Kneller and Branney, 1995). Heterolithic

clasts distributed throughout valley-fill profiles reflect

several nonlocal sources of sediment. Clasts have

therefore been transported from up to 15–20 km up-

valley and deposited together.

Horizontally bedded and massive silt and sand

lenses suggest planar bed upper- and lower-flow

regimes. Horizontally bedded thin intercalated units

or dcoupletsT of granules and pebbles are similar to

those described by Carling (1990) in association with

scour and fill. Alternatively, and more likely, they

simply suggest shallow but variable flow conditions.

Dipping beds of granules and sand occur due to

prograding sheets of sediment, i.e., the passage of

shallow relief bedforms (Allen, 1985).

6.2. Tributary mouth sediments

Tributary mouth sediments alongside Hraundalur

(Figs. 3 and 4) are also interpreted to be the product of

subaerial flows. Tributary mouth deposits have not

originated from the tributary valley itself, because

within a single kilometre, all of the valleys become a

dcul-de-sacT, having no point upslope from which

flow might influx. Thus, tributary mouth deposits do

not consist of locally derived slope material, rather

deposits entirely comprise exotic material. Tributary

valley sediments must therefore be products of flows

from the main Hraundalur valley entering and backing

up into a tributary valley. In this respect, valley mouth

Fig. 5. Section through a subaerial lava flow in Kverkfjallarani. The

subaerial lava has inundated dwetT jfkulhlaup deposits, resulting in afragmented dhyaloclastiteT base to the flow. It is unclear how much

time (if any) may have passed between the jfkulhlaup and the lava

flow event.

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 31

deposits can be termed as slack water deposits (Baker,

1973; Baker et al., 1983; Carling et al., 2002). For

note, slack water is used as a relative term, for flows

in these areas contained circulatory currents and were

far from stationary. The thickness of sediments

(greater than 3 m) and the size of clasts suggest

deposition from high-magnitude flow(s). Furthermore,

Hraundalur only experiences spring snowpack melt

and no other regular overland flow. Slack water

deposits cannot be due to a very high river discharge,

because there is no perennial river. Jfkulhlaupprocesses therefore seem to be the only explanation

for the emplacement and character of tributary valley

sediments. This argument is substantiated still further

with reference to the character of the slack water

sediments.

Slack water sediments are essentially similar to the

valley-fill sediments within Kverkfjallarani, albeit

with smaller grain sizes. Such variability in unit

structure and texture could indicate considerable and

abrupt alterations in flow hydraulics and/or sediment

supply during a single event or many individual

events (Allen, 1985). Alternatively, variability may be

due to pulses of sediment supply or flow within an

event.

Bedded lenses and fine grain beds, which separate

flood units, indicate multiple jfkulhlaups. This silt

and grains are predominantly palagonite (Fig. 5).

Palagonite is derived from slope wash off local

pillow lava ridges and mounds. If a high-magnitude

flood had transported this palagonite, the deposit

would be interspersed with basaltic sands and silts of

equivalent size and density. The fact that palagonite

beds are homogenous implies a local and low-energy

deposition process. Such events might be snowmelt,

slush flows and rainwash with sediment from local

slopes for example. Alternatively floodwaters may

have become ponded by flood bars, and sediment

conveyed into the pond by aeolian or volcanic airfall

settled out from suspension. Therefore, palagonite

beds either pre- or postdate a flood event. Where

flood units are found above and below a palagonite

bed (pits 3 and 5), and multiple palagonite beds

occur (pits 3 and 5), a number of jfkulhlaup events

can be identified. In total and by taking into account

erosional contacts, bedded silt lenses and palagonite

beds, three jfkulhlaup events within pits 1 to 5 can

be identified (Fig. 3).

Structureless units containing granules and small

pebbles within a poorly sorted fine-grained matrix are

interpreted as products of hyperconcentrated flow

conditions (Costa, 1988). These units are therefore

indicative of high-magnitude flows, because they are

incompatible with a hypothesis of dnormalT sedimen-

tation. Hyperconcentrated units dominate the lower-

most sections of the excavated pits. Poorly sorted,

clast-supported and imbricated small pebble units are

interpreted to represent grain by grain deposition from

traction load within a high-energy turbulent flow

(Brayshaw, 1984). Horizontally bedded and poorly

sorted sands and granules that are ungraded likely

reflect deposition from a turbulent suspension prior to

late-stage traction transport (Brennand, 1994). Dip-

ping beds probably reflect an advancing or prograding

shallow relief bedform. The orientation of these dips

shows that these sediments prograded up into the

tributary valley. Graded sand and granule beds

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4032

represent pulses of tractive bed load with fluctuating

energies. Shallow and low-energy flows at pit 6 have

produced small (mm–cm) scale flaser and lenticular

bedding (Fig. 4). This site, which is ~1 km from the

main Hraundalur channel, was thus inundated by a

regime of multiple fluctuations between shallow flow

with spatially varying low-energy currents and sta-

tionary water. Deposition varied in time and space

between suspension dropout and low-energy traction.

Granular lenses have a chaotic appearance (Fig. 4),

probably reflecting slumping within the saturated

sediments or water-table pressure disturbance, perhaps

from slush avalanches or another jfkulhlaup for

example. Fining-upwards units reflect waning stage

deposition as competence decreased. The prolific

nature of heterolithic and volcaniclastic clasts reflects

multiple and nonlocal sources of sediment. Surface

pebble lags are likely to be due to a combination of

several processes including frost heave action, win-

nowing by waning stage flows and winnowing by

aeolian action.

6.3. Summary of interpretation

Valley-fill deposits within Kverkfjallarani are con-

sistent with a high-magnitude hyperconcentrated and

fluidal flow. Given the environmental and local

situation of the deposits and the absence of surface

drainage in this area, the high-magnitude flows were

most likely jfkulhlaups from Kverkfjfll. The com-

plexity and multifaceted nature of the units imply the

passage of several high-magnitude jfkulhlaups or a

single jfkulhlaup with a highly variable flow regime.

In either case, the fact that valley-fill sediment is

derived from nonlocal sources and that both tractive

and suspended deposits are present together shows

that jfkulhlaup flow(s) had extremely variable

hydraulics and sediment supply, both spatially and

temporally. These deposits are similar to those

suggested by Kneller and Branney (1995) and

documented by Manville and White (2003), who

inferred a volcaniclastic sediment-laden flow with a

granular base flow. However, because uppermost beds

of valley-fill sediments comprise extensive sheets of

granules and imply prograding shallow bedforms,

flows progressed to a rather more fluidal flow.

Tributary mouth deposits within Kverkfjallarani

are interpreted as slack water deposits (Baker et al.,

1983), which are the result of high-magnitude flows

that have backed up into tributary valleys from

Hraundalur. Like valley-fill sediments, slack water

deposits within Kverkfjallarani are a product of

initially sediment-laden or hyperconcentrated flows

that subsequently became more fluidal.

7. Discussion: properties of jokulhlaups from

Kverkfjoll

Several inferences may be made concerning the

number, age and hydraulics of the Kverkfjallarani

jfkulhlaups. Carrivick et al. (in press) describe several

locations within Kverkfjallarani where an older

jfkulhlaup surface has become overlain by a post-

glacial subaerial lava flow. Several postglacial lava

flows within Kverkfjallarani are a product of an

eruption of the Biskupsfell fissure (Karhunen, 1988).

Some Biskupsfell fissure lava flows display evidence

of erosive dwashingT by jfkulhlaups (Carrivick et al.,

in press). Jfkulhlaups through Kverkfjallarani there-

fore both pre- and postdate the Biskupsfell fissure

eruption.

An exposure of a section through part of a

subaerial lava flow reveals fragmented hyaloclastite

at the base of subaerial units (Fig. 5). Beneath the

hyaloclastite lie a series of laterally continuous sand

beds inundated by thin granular sheets. This section

represents a subaerial lava that has overrun and cooled

in contact with dwetT jfkulhlaup sediments overlain by

a pond of water. Therefore, Fig. 5 is suggestive of

jfkulhlaup and volcanic event coupling, because the

lava flow has been erupted whilst the jfkulhlaupsediments were ponded and because superficial water

or snow in Kverkfjallarani rarely survives a summer

season. Therefore, jfkulhlaups are probably linked

with fissure eruptions within the Kverkfjfll VolcanicSystem (KVS).

Jfkulhlaups through Kverkfjallarani also appear

to have been associated with much larger

jfkulhlaups that routed from the Dyngjujfkull ice

margin. Fig. 6 illustrates how jfkulhlaup evidence at

the northernmost extent of Hraundalur merges with

the Krepputungahraun. The Krepputungahraun itself

has been severely scoured by a jfkulhlaup flow from

the Dyngjujfkull ice margin. There is no evidence to

suggest that the Hraundalur jfkulhlaup deposits

washed over the Krepputungahraun, and therefore

Fig. 6. Cross-cutting evidence for two jfkulhlaups from the Dyngjujfkull ice margin (a). It is unclear whether the first jfkulhlaup from the

Dyngjujfkull ice margin coincides with or postdates the last jfkulhlaup that exited from Hraundalur (the Kverkfjfll ice margin). An example of

the scoured and plucked nature of the Krepputunguhraun is given (b) and located on (a).

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 33

we assume either that the Hraundalur flows were of

an insufficient magnitude to deposit that lava, or that

the Krepputangahraun was erupted after the Hraun-

dalur jfkulhlaups. The scoured Krepputungahraun

has been subject to tectonic faulting after jfkulhlaup1, from the Dyngjujfkull ice margin. After this

tectonic activity, the Kverkfjallahraun was erupted

and its route partly determined by the tectonic faults

(Fig. 6). At its margins near Lindafjfll, the Kverkf-

jallahraun is not eroded and supports no sedimentary

deposits; it appears dfreshT. However, near the

present-day course of the Jfkulsa a Fjfllum, the

Kverkfjallahraun is smoothed, scoured and has

cobbles and boulder material upon it. This texture

is evident even from an aerial photograph (Fig. 6). A

second jfkulhlaup is inferred to have routed across

the Kverkfjallahraun. This flood is informally

labelled as jfkulhlaup 2. Jfkulhlaup 2 from the

Dyngjujfkull ice margin may well be the same

jfkulhlaup as that from Hraundalur, or it might have

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4034

been a separate event but lies in the same strati-

graphic context.

Along Hraundalur, each distal slack water (pits 1–

5) has been inundated by three separate jfkulhlaups.Basaltic fine sand beds stratigraphically separate these

jfkulhlaups from each other (Fig. 3). The major-

element composition of the basaltic fine sand is

similar to that of other silica-poor tephras or of

Biskupsfell airfall (Table 2). Table 2 illustrates that it

is not possible to discriminate between the suspected

tephra samples of this study or between those and

known tephra samples documented elsewhere. Fur-

thermore, the high loss on ignition (LOI) values

(N1%) indicate that if these are tephra, they have

become altered. It is therefore possible that the

samples of this study are variations of previously

recorded tephra or that the samples are in fact a new

tephra that has not been previously documented.

Given the lack of tephra data from the central

highlands of Iceland (Newton, 1996, 2003), either

scenario is quite possible. A third and most likely

possibility for the genesis of fine-grained basaltic beds

is that of slope-washed palagonite. Because palagonite

is a hydrated and weathered product from the outer

sections of pillow lava (Cas and Wright, 1988), we

suggest that fine-grained beds of palagonite may form

between jfkulhlaups as successive slush flows,

avalanches and rain storms, for example, wash

Table 2

Constituent major elements by percentage of tephra sample

Sample SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na

Pit 5 (1) 45.2 3.7 14.9 16.3 0.3 5.4 6.0 1.2

Pit 5 (2) 47.2 3.2 14.3 15.4 0.2 4.9 6.1 1.4

Pit 5 (3) 49.5 2.6 13.7 14.6 0.2 5.2 8.2 2.0

Pit 5 (4) 46.2 3.5 13.9 16.4 0.2 4.9 5.7 1.2

Pit 3 (1) 47.3 3.2 13.1 17.1 0.3 5.0 8.7 2.6

Pit 3 (2) 43.9 3.6 14.2 17.1 0.2 4.3 6.2 1.2

Mjauvotn dAT 46.7 4.2 12.9 14.5 0.3 4.9 10.1 3.1

Hekla1104 48.7 2.6 13.1 13.1 0.2 5.9 10.6 2.6

Katla1000K-X 46.3 4.7 12.6 14.5 0.2 4.9 9.4 3.2

Landman 49.9 2.0 13.4 12.1 0.2 6.2 10.7 2.6

Saksunarvatn 48.6 3.0 13.0 13.8 0.3 5.7 9.9 2.7

SWVeidivotn 48.9 1.8 13.5 11.4 0.2 7.5 11.8 2.4

Biskupsfell airfall 48.4 3.1 12.8 15.4 0.2 4.9 9.3 3.1

Akja 1875 69.6 1.0 13.4 5.2 0.1 1.2 3.3 3.6

Akja 1875 71.6 0.8 12.7 3.5 0.1 0.7 2.4 3.5

A number of Icelandic tephras that are low in silica and data from the Bisk

within Kverkfjfll jfkulhlaup slack water pits.

material off hillsides. Crucially, palagonitized pillow

lava rinds will have very similar major-element

composition as the basaltic tephra (Table 2).

Whether the basaltic fine sand is volcanic tephra

or slope-washed palagonite, we can conclude that a

break in the jfkulhlaup deposition occurred of

duration sufficient for another process(es) to deposit

sediment. Therefore, at least three jfkulhlaups have

inundated the areas of pit 3 and 5 (Fig. 3). This

conclusion probably holds for pits 1, 2 and 4 as well,

because they also contain beds of basaltic silt and

fine sand (Fig. 3). To put an absolute date against

any of these jfkulhlaups is currently impossible,

because jfkulhlaup sediments are simply reworked

material and the volcanic material cannot be matched

to a specific eruption. Furthermore, absence of

nonjfkulhlaup units within pits 1, 2 and 4 does not

necessarily mean that these pits did not experience

the same interruptions in jfkulhlaup deposition as

pits 3 and 5. Pits 1, 2 and 4 are closer to Hraundalur

than pits 3 and 5 and are therefore likely to have

experienced higher energy flows than that at pits 3

and 5. Therefore, a jfkulhlaup at sites 1, 2 and 4

could easily have had the capacity to erode fine-

grained tephra or slope-washed palagonite before

emplacing slack water sediments.

Given that slack water sediments mark the highest

elevations within a jfkulhlaup, they can be used as

2O K2O P2O5 Loss on

ignition

Total No. of

samples

Reference

0.6 0.4 6.0 100.0 2 This study

0.6 0.3 5.9 99.5 2 This study

0.6 0.3 2.8 99.6 2 This study

0.6 0.3 6.5 99.4 2 This study

0.6 0.3 1.3 99.4 2 This study

0.5 0.3 7.9 99.2 2 This study

0.8 97.3 19 Data is sourced

from Newton,

2003

0.4 97.3 6 (12)

0.8 96.6 20

0.3 97.5 59

0.4 97.3 30

0.2 97.5 6

0.6 0.4 8 Karhunen (1988)

2.0 0.2 0.4 100.04 2 This study

2.4 97.7 36 Newton (2003)

upsfell fissure eruption are given for comparison with tephra found

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 35

palaeostage indicators (Kochel and Baker, 1988).

Slack water surface altitudes were measured from a

Digital Elevation Model (DEM) of the Kverkfjallarani

area and accompany observations of wash limits. Wash

limits within Kverkfjallarani include valley-marginal

terraces, bars, scour and deposition (Carrivick et al., in

press). However, the most distinct wash limits within

Kverkfjallarani are ridge (valley wall) flank deposits of

exotic, heterolithic and well-rounded small pebbles

and coarse granules (Carrivick et al., in press).

Slope–area calculations of the largest jfkulhlaup to

have occurred along Hraundalur produce a variety of

results depending upon the method used (Fig. 7). The

Jarrett method (Jarrett, 1984), which relies upon the

hydraulic radius parameter rather than specific form

Fig. 7. Slope–area calculations of peak discharge based upon field and DEM

used in the calculations are shown.

and grain roughness values for its resistance term,

suggests an average peak discharge value of 29,400

m3 s�1. The Thompson and Campbell (1979) method

includes a term for the relative protrusion of resistance

elements into the flow depth and yields average peak

discharge estimates for Hraundalur of 46,300–54,600

m3 s�1. A similar average value of 49,300 m3 s�1 is

obtained by the Manning–Strickler method (Strickler,

1923) that incorporates a grain resistance factor of

transported sediment. The Manning–Limerinos

method that adds a relative roughness element to the

grain resistance factor (Limerinos, 1970) produces

average values of 35,500–46,400 m3 s�1. It should be

noted that within Hraundalur, we estimate that our

wash limits and slack water elevations are accurate to

measurements. NB. For clarity, only a few of the 124 cross-sections

Fig. 8. Peak discharges estimated by slope–area methods along Hraundalur. Different methods produce a range of estimates, depending upon

how they parameterise roughness. However, the rapid downstream attenuation of peak discharge is consistent between methods. Discharge

attenuation seems to be more closely linked to the channel topography than by spillways (black arrows). Spillways are flows exiting from the

Hraundalur valley.

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4036

1 m, based upon the agreement of DGPS, GPS and

DEM measurements. Within the widest and shallow-

est cross-sections, this might produce an error in the

estimate of discharge by up to 25%. Although this is

the highest probable error, there is variability within

the Hraundalur estimates of discharge, not least

because the channel frequently diverges around

ridges. This paper does not attempt to analyse the

differences in the methods and assumptions between

the different slope–area methods. Interestingly, there

is a notable decrease in peak discharge downstream.

All four methods record the same downstream

attenuation of some 50–70% decrease in peak

discharge in just 25 km (Fig. 8). This attenuation is

mostly attributable to high roughness values rather

than spillways (Fig. 8). The steepest sections of the

Table 3

Properties of jfkulhlaups from Kverkfjfll; a glaciated volcano within an a

Properties of jokulhlaups within Kverkfjallarani; an active volcanic rifting

Channel Steep V

High resistance F

Trigger Volcanogenic (

Hydraulics R

High velocities S

High discharges S

Sedimentology and rheology Bimodal S

Phase I

Variable R

channel are those where subaerial lava flows are

exposed and terminate. The shallowest channel

sections are between lava flows and are sediment

traps. It follows that most energy loss and hence

attenuation of peak discharge will occur across steeper

and rougher lava surfaces.

Jfkulhlaups along Hraundalur present a model of

the main controls on characteristics of jfkulhlaupswithin an active volcanic rifting zone (Table 3; Fig. 9).

This model illustrates deposition on both the rising

(Fig. 9a) and falling (Fig. 9b) stages of the hydrograph

and results in a distinctive suite of sedimentary impacts

(Fig. 9c). With respect to the sedimentary impacts of

jfkulhlaups within other environments, models of

jfkulhlaup characteristics need to be altered to include

the effects of high sediment availability and high-

ctive volcanic rifting zone

zone

alley gradients commonly 0.02 and greater water surface gradients

rom roughness elements up to 30% of flow depth

Either with or without intermediary storage)

elatively shallow (N10 m) anastomosing flows

lope–area calculations suggest typically N20 m s�1

lope–area calculations suggest minimum of 50,000 m3 s�1

upply limited to subaerial lava boulders and pillow bricks

nitially non-Newtonian, then more fluidal

apid downstream attenuation of discharge

Fig. 9. Overview conceptual model of controls on and nature of bedrock-channelled jfkulhlaup sedimentation within a volcanic rifting

landscape. (a) Rising and peak stage, (b) waning stage, (c) overview of sedimentary products including slack water deposits (S), terraces (T) and

valley-fill deposits (Vf).

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 37

gradient, hydraulically rough routeways. These factors

control the consequential high transmission losses and

rapid downstream attenuation of peak discharge.

8. Conclusions

This study provides a suite of sedimentary impacts

that evidence jfkulhlaups from Kverkfjfll volcano and

has suggested many characteristics of these jokulhla-

ups. Slack water stratigraphy shows that at least three

jfkulhlaups routed through Hraundalur at a similar

time to the Biskupsfell eruption. Valley-fill sediments

and slack water sediments illustrate that these

jfkulhlaups were typically hyperconcentrated but

became more fluidal. Slope–area calculations suggest

that the largest jfkulhlaup through Hraundalur had a

peak discharge of 45,000–55,000 m3 s�1, although this

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4038

discharge attenuated by 50–70% in just 25 km. This

attenuation and thus hydrograph modification were

determined by the interplay of many external and

internal controls (Carrivick et al., in press), but

particularly of the jfkulhlaup source upon a glaciated

volcano and its passage through a steep and hydrauli-

cally rough volcanic landscape. Therefore, a variety of

external and internal controls modified the hydrograph

shape and thus exerted controls on large-scale sedi-

mentary impacts (Rushmer et al., 2002).

9. Wider implications

It is anticipated that this model of sedimentary

characteristics of jfkulhlaups from Kverkfjfll will beapplicable to other outburst floods from glaciated

volcanoes and/or within active volcanic rifting zones.

Estimates of the hydraulic properties of jfkulhlaupsfrom Kverkfjfll will enable examination of sediment

entrainment mechanisms, sediment volumes within

flows, erosional and depositional thresholds and

landform evolution for example. Furthermore, flood

hazard mapping, risk assessment and mitigation

measures can be introduced, given knowledge of the

source, routeway and behaviour of jfkulhlaups.Finally, estimates of sudden discharges of freshwater

and sediment from the north coast of Iceland during

deglaciation may provide information regarding

potential triggers of abrupt changes in thermohaline

circulation and hence regional climatic changes in the

North Atlantic (Manabe and Stouffer, 1995; Rahm-

storf, 1995, 1997). Teller et al. (2002) have already

discussed the effects of similar inputs to the North

Atlantic from the American continent.

Acknowledgements

We thank the Icelandic Research Council and the

Nature Conservation Agency for permission to under-

take research in northern Iceland. JLC gratefully

acknowledges the receipt of grants from BGRG,

IAS and QRA for aerial photograph acquisition and

field assistant costs. AJR received a Royal Society

grant for fieldwork in 2000. The Earthwatch Institute

funded the fieldwork during the summers of 2000,

2001, 2002 and 2003. A very special thank you to all

of the 2000 Earthwatch Team III and the 2001, 2002

and 2003 Earthwatch Team IV volunteers and to Oly

Lowe and Hugh Deeming for invaluable field

assistance. Hauker, Rachel, Sira, Loftur and Edda

and Elisabet made us very welcome at Sigurdarskali.

JLC thanks Dave Emley for his XRF guidance and Ian

Wilshaw for his support in the sediments laboratory.

Aslaug Geirsdottir and Paul Carling provided con-

structive critical reviews on an earlier version of the

manuscript.

References

Allen, J.R.L., 1985. Principles of Physical Sedimentology. Allen

and Unwin, London. 272 pp.

Baker, V.R., 1973. Palaeohydrology and sedimentology of Lake

Missoula flooding in eastern Washington. Special Paper -

Geological Society Of America 144, 1–79.

Baker, V.R., Kochel, R.C., Patton, P.C., Pickup, G., 1983. Palaeo-

hydrologic analysis of Holocene flood slackwater sediments.

Special Publication of the International Association of Sedi-

mentologists 6, 229–239.

Bjfrnsson, H., 1988. Hydrology of Ice Caps in Volcanic Regions.

Visingdafelag Islendinga, Reykjavik. 44pp+map plates pp.

Bjfrnsson, H., 1992. Jfkulhlaups in Iceland: prediction, characte-

ristics and simulation. Annals of Glaciology 16, 95–106.

Bjfrnsson, H., 2002. Subglacial lakes and jfkulhlaups in Iceland.

Global and Planetary Change 35, 255–271.

Bjfrnsson, H., 1991. Volcanoes beneath Vatnajfkull, Iceland:

evidence from radio-echo sounding, earthquakes and

jfkulhlaups. Jfkull 40, 147–168.Bluck, B.J., 1974. Stuctural and directional properties of some

valley sandur deposits in southern Iceland. Sedimentology 21,

553–554.

Boothroyd, J.C., Ashley, G.M., 1975. Processes, bar morphology

and sedimentary structures on braided outwash fans, north-

eastern Gulf of Alaska. In: Jopling, A.V., McDonald, B.C.

(Eds.), Glaciofluvial and Glaciolacustrine sedimentation, SEPM

Special Publication 23, pp. 193–222.

Brayshaw, A.C., 1984. Characteristics and origin of cluster

bedforms in coarse-grained alluvial channels. In: Koster,

E.H., Steel, R.J. (Eds.), Sedimentology of Gravels and

Conglomerates. Canadian Society of Petroleum Geologists,

pp. 77–85.

Brennand, T.A., 1994. Macroforms, large bedforms and rhythmic

sedimentary sequences in subglacial eskers, south-central

Ontario: implications for esker genesis and meltwater regime.

Sedimentary Geology 91, 9–55.

Carling, P.A., 1990. Particle over-passing on depth-limited gravel

bars. Sedimentology 37, 345–355.

Carling, P.A., 1996. Morphology, sedimentology and palaeohy-

draulic significance of large gravel dunes, Altai Mountains,

Siberia. Sedimentology 43, 647–664.

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–40 39

Carling, P.A., Kirkbride, A.D, Parnachov, S., Borodavko, P.S.,

Berger, G.W., 2002. Late Quaternary catastrophic flooding in

the Altai mountains of south-central Siberia: a synoptic over-

view and an introduction to flood deposit sedimentology. In:

Martini, P.I., Baker, V.R., Garzon, G. (Eds.), Flood and

Megaflood Processes and Deposits: Recent and Ancient

Examples, Spec. Publs Int. Ass. Sedment, pp. 17–35.

Cas, R.A.F., Wright, J.V., 1988. Volcanic Successions: Modern and

Ancient. Unwin Hyman, London. 528 pp.

Carrivick, J.L., Russell, A.J., Tweed, F.S., in press. Geomorpho-

logical evidence for jfkulhlaups from Kverkfjfll volcano,

Iceland. Geomorphology.

Collinson, J.D., 1970. Bedforms of the Tana River, Norway.

Geographiska Annaler 52A, 31–56.

Costa, J.E., 1988. Rheologic, geomorphic and sedimentologic

differentiation of water flows, hyperconcentrated flows and

debris flows. In: Baker, V.R., Kochel, R.C., Patton, P.C. (Eds.),

Flood Geomorphology. Wiley, New York, pp. 113–122.

Costa, J.E., Schuster, R.L., 1988. The formation and failure of

natural dams. Geological Society of America Bulletin 100,

1054–1068.

Eliasson, S., 1977. Molar um Jfkulsarhlaup og Asbyrgi. Nattu-

rufr&ðingurinn 47, 160–179.

Fay, H., 2002a. Formation of kettle holes following a glacial-

outburst flood (jfkulhlaup), Skeiðararsandur, southern Iceland.

In: Snorasson, A., Finnsdottir, H.P., Moss, M. (Eds.), The

Extremes of The Extremes: Extraordinary floods. IAHS

Publication no. 271, pp. 205–210.

Fay, H., 2002b. Formation of ice-block obstacle marks during the

November 1996 glacier-outburst flood (jfkulhlaup), Skeiðar-

arsandur, southern Iceland. Special Publications International

Association of Sedimentology 32, 85–97.

Guðmundsson, H.J., 1997. A review of the Holocene environ-

mental history of Iceland. Quaternary Science Reviews 16,

81–92.

Guttormson, H., 1987. Norð-Austurland—Halendi og Eyðibyggðir

(highlands and uninhabited areas). Ferðafelag Islands Arbok.

Ferðafelag Islands, Reykjavik.

Haerberli, W., 1983. Frequency and characteristics of glacier floods

in the Swiss Alps. Annals of Glaciology 4, 85–90.

Helgason, J. 1987. Jarðfr&ðirannsoknir a Vatnasviði Jfkulsar a

Fjfllum við Mfðrudal. Report OS-87005/VOD-01: Orkustof-nun Reykjavık.

Jarrett, R.D., 1984. Hydraulics of high gradient streams. Journal of

Hydraulic Engineering 110, 1519–1539.

Jones, A.P., Tucker, M.E., Hart, J.K., 1989. Guidelines and

recommendations. In: Jones, A.P., Hart, J.K., Tucker, M.E.

(Eds.), The description and analysis of Quaternary Stratigraphic

Field Sections. Quaternary Research Association Technical

Guide No.7. QRA London, pp. 27–76.

Johannesson, H., Saemundsson, K., 1989. Geological map of

Iceland, 1:1500 000 Bedrock geology. Icelandic Museum of

Natural History and Icelandic Geodetic Survey, Reykjavık.

Karhunen, R., 1988. Eruption mechanism and rheomorphism during

the basaltic fissure eruption in Biskupsfell, Kverkfjoll, north-

central Iceland. Nordic Volcanological Institute 8802 (Reykja-

vik. 91 pp.).

K7yhko, J., Alho, P., Hendriks, J.P.M., Rossi, M., 2002. Geo-

morphological processes and land degradation in Odaðahraun

semi-desert, north-eastern Iceland. Jfkull 51, 1–16.Kehew, A.E., 1993. Glacial-lake outburst erosion of the Grand

Valley, Michigan and impacts on glacial lakes in the Lake

Michigan Basin. Quaternary Research 39, 36–44.

Kneller, B.C., Branney, M.J., 1995. Sustained high-density turbidity

currents and the deposition of thick massive sands. Sedimento-

logy 42, 607–616.

Knudsen, O., Russell, A.J., 1995. Jfkulhlaup deposits at the

Asbyrgi Canyon, northern Iceland: sedimentology and implica-

tions for flow type. Proceedings of The Extremes of The

Extremes symposium, Reykjavik, Iceland, IAHS Publication,

vol. 271.

Kochel, R.C., Baker, V.R., 1988. Palaeoflood analysis using

slackwater deposits. In: Baker, V.R., Kochel, R.C., Patton,

P.C. (Eds.), Flood Geomorphology, pp. 357–376.

Limerinos, J.T., 1970. Determination of the Manning coeffiecient

from measured bed roughness in natural channels. United States

Geological Water Supply Paper 1898-B (47 pp.).

Maizels, J.K., 1989. Sedimentology, palaeoflow dynamics and flood

history of jfkulhlaup deposits: paleohydrology of Holocene

sediment sequences in southern Iceland sandur deposits. Journal

of Sedimentary Petrology 59, 204–223.

Maizels, J.K., 1991. The origin and evolution of Holocene

sandur deposits in areas of jfkulhlaup drainage, Iceland. In:

Maizels, J.K., Caseldine, C. (Eds.), Environmental Change

in Iceland: past and present. Kluwer Academic Publishing,

pp. 267–299.

Maizels, J.K., 1993. Lithofacies variations within sandar deposits:

the role of runoff regime, flow dynamics and sediment supply

characteristics. Sedimentary Geology 85, 299–325.

Maizels, J.K., 1995. Sediments and landforms of modern proglacial

terrestrial environments. In: Menzies, J.E. (Ed.), Modern Glacial

Environments. Butterworth-Heinemann, Oxford, pp. 365–416.

Maizels, J.K., 1997. Jfkulhlaup deposits in proglacial areas.

Quaternary Science Reviews 16, 793–819.

Maizels, J., Russell, A.J., 1992. Quaternary perspectives on

jfkulhlaup prediction. Quaternary Proceeedings 2, 133–152.

Manabe, S., Stouffer, R.J., 1995. Simulation of abrupt climate

change induced by freshwater input to the North Atlantic Ocean.

Nature 378, 165–167.

Manville, V., White, J.D.L., 2003. Incipient granular mass flows at

the base of sediment-laden floods, and the roles of flow

competence and flow capacity in the deposition of stratified

bouldery sands. Sedimentary Geology 155, 157–173.

Marren, P.M., 2003. Criteria for distinguishing high magnitude

flood events in the proglacial fluvial sedimentary record.

Proceedings of The Extremes of The Extremes symposium,

Reykjavik, Iceland, IAHS Publication, vol. 271.

Miall, A.D., 1977. A review of the braided river environment. Earth

Science Reviews 13, 1–62.

Miall, A.D., 1985. Architectural-element analysis: a new method of

facies analysis applied to fluvial deposits. Earth Science

Reviews 22, 263–308.

Nemec, W., Steel, R.J., 1984. Alluvial and coastal conglomerates:

their significant features and some comments on gravelly mass

J.L. Carrivick et al. / Sedimentary Geology 172 (2004) 19–4040

flow deposits. In: Koster, E.H., Steel, R.J. (Eds.), Sedimentol-

ogy of gravels and conglomerates. Canadian Society of

Petroleum Geologists, pp. 1–31.

Newton, A.J., 1996. Tephrabase. A tephrochronological database.

Quaternary Newsletter 78, 8–13.

Newton, A.J., 2003. Tephrabase. http://www.geo.ed.ac.uk/tephra/

(visited 16/11/03).

Olafsdottir, R., Guðmundsson, H.J., 2002. Holocene land degrada-

tion and climatic change in northeastern Iceland. The Holocene

12 (2), 159–167.

Rahmstorf, S., 1995. Bifurcations of the Atlantic thermohaline

circulation in response to changes in the hydrological cycle.

Nature 378, 145–149.

Rahmstorf, S., 1997. Risk of sea-level change in the Atlantic.

Nature 388, 825–826.

Rushmer, E.R., Russell, A.J., Tweed, F.S., Knudsen, O., Marren,

P.M., 2002. The role of hydrograph shape in controlling glacier

outburst flood (jfkulhlaup) sedimentation. The Structure,

Function and Management of Fluvial Sedimentary Systems

Proceedings of an international symposium held in Alice

Springs, Australia, September 2002, IAHS Publication, vol.

276, pp. 305–313.

Russell, A.J., 1993. Obstacle marks produced by flow around

stranded ice blocks during a glacier outburst flood (jfkulhlaup)in west Greenland. Sedimentology 40, 1091–1111.

Russell, A.J., Marren, P.M., 1999. Proglacial fluvial sedimentary

sequences in Greenland and Iceland: a case study from active

proglacial environments subject to jfkulhlaups. In: Jones, A.P.,Hart, J.K., Tucker, M.E. (Eds.), The description and analysis

of Quaternary Stratigraphic Field Sections. Quaternary

Research association technical Guide No.7. QRA London,

pp. 171–208.

Saemundsson, K., 1973. StraumrakaWar klappir ı kringum Asbyrgi.

Natturufr&ðzingurinn 43, 52–60.

Smith, N.D., 1974. Sedimentology and bar formation in the upper

Kicking Horse River, a braided outwash stream. Journal of

Geology 82, 205–223.

Sohn, Y.K., 1997. On traction carpet sedimentation. Journal of

Sedimentary Research 67, 502–509.

Strickler, A., 1923. Beitrage zur Frage der Geschwindigheitsformel

und der Rauhigkeitszahlen fur Strome, Kanale und Geschlos-

sene Leitungen. Mitteilungen des Eidgenossischer Amtes fur

Wasserwirtschaft, Bern, Switzerland, p. 16.

Teller, J.T., Leverington, D.W., Mann, J.D., 2002. Freshwater

outbursts to the oceans from glacial Lake Agassiz and their role

in climate change during the last deglaciation. Quaternary

Science Reviews 21, 879–887.

Thompson, S.M., Campbell, P.L., 1979. Hydraulics of a large

channel paved with boulders. Journal of Hydraulic Research 17,

341–354.

Thorarinsson, S., 1950. Glacier outbursts in the river Jfkulsa a

Fjfllum. Natturufr&ðingurinn 20, 113–133.

Todd, S.P., 1989. Stream-driven, high density gravelly traction

carpets: possible deposits in the Trabeg Conglomerate For-

mation, SW Ireland and some theoretical considerations of their

origin. Sedimentology 36, 513–530.

Tomasson, H., 1973. Hamfarahlaup ı Jfkulsa a Fjfllum. Nattu-

rufr&ðingurinn 43, 12–34.

Tomasson, H., 2002. Catastrophic floods in Iceland. The Extremes

of The Extremes: Extraordinary Floods, Proceedings of a

symposium held at Reykjavik, Iceland, July 2000 (IAHS Publ.

no. 271), pp. 121–126.

Waitt R.B. 1998. Cataclysmic flood along Jfkulsa a Fjfllum,

north Iceland, compared to repeated colossal jfkulhlaups of

Washington’s channelled scabland. 15th Int. Sediemntol.

Congr., Alicante, 811– 812.

Waitt, R.B., 2002. Great Holocene floods along Jfkulsa a Fjfllum,

north Iceland. In: Martini, P.I., Baker, V.R., Garzon, G. (Eds.),

Flood and Megaflood Processes and Deposits: Recent and

Ancient Examples, Special Publications International Associa-

tion of Sedimentology, pp. 37–51.