the sedimentology of middle holocene tsunami facies in northern sutherland, scotland, uk

The sedimentology of Middle Holocene tsunami facies innorthern Sutherland, Scotland, UK

S. Dawson*, D.E. Smith

Centre for Quaternary Science, Geography, School of Natural and Environmental Sciences, Coventry University, Priory Street,

William Morris Building, Coventry CV1 5FB, UK

Received 1 February 1999; accepted 1 September 1999

Abstract

Lagoonal sediments attributed to the main Holocene marine transgression in Strath Halladale, northern Sutherland, contain a

complex coarser layer believed to have been deposited during the tsunami associated with the Second Storegga Slide off South

West Norway. The coarser sequence is dated at between 7590 ^ 50 and 7290 ^ 50 radiocarbon years BP (6507±6260 cal BC

and 6228±6029 cal BC). Detailed stratigraphical analysis has determined a distinctive suite of sedimentary sub-units within the

coarser layer in marked contrast to the sediments, which occur above, and below. A pronounced erosional unconformity with

the underlying sediments is recorded with the base of the tsunami layer characterised by eroded material from the underlying

peat. The presence of a mixed diatom assemblage, although fragmentary, indicates a chaotic accumulation of the deposit with all

habitats represented. Variations in particle size within the sequence disclose striking similarities with those from contemporary

tsunami deposits. The run-up of the tsunami sediments is calculated at a minimum of 4.6 m. This is the ®rst occasion on which a

deposit of the Second Storegga Slide tsunami has been found outside the North Sea basin and indicates that the area affected by

the tsunami may have been larger than has been previously described. q 2000 Elsevier Science B.V. All rights reserved.

Keywords: Tsunami; Holocene; Diatoms; Sedimentology

1. Introduction

Tsunamis are seismic sea waves caused by distur-

bance of the sea ¯oor during earthquakes, volcanic

eruptions or submarine landslides. These long waves

(up to 200 km) travel over the ocean at great velocity.

Within the open ocean, the wave height is low, but

upon reaching shallow water, in the vicinity of the

coastline, it becomes greatly ampli®ed. Therefore,

the impact at the coast is often catastrophic (e.g. the

Papua New Guinea tsunami of July 1998 led to the

death of at least 2000 people).

Within a geological timescale, a tsunami is a low-

frequency high-magnitude event. Several studies of

sedimentation associated with contemporary tsunami

inundation have been undertaken, for example by Yeh

et al. (1993) and Dawson (1996). These disclose

complex patterns with large-scale movement of

sediment both in onshore and seaward direction.

Recent years have seen a proliferation of sedimento-

logical studies of inferred tsunami sediments from the

geological record (e.g. Dawson et al., 1988, 1995;

Bourgeois et al., 1988; Minoura et al., 1994; Shi,

1995; Dawson et al., 1996; Dawson and Smith, 1997;

Goff and ChagueÂ±Goff, 1999b; Goff et al., 2000).

Marine Geology 170 (2000) 69±79

0025-3227/00/$ - see front matter q 2000 Elsevier Science B.V. All rights reserved.

PII: S0025-3227(00)00066-9

www.elsevier.nl/locate/margeo

* Corresponding author.

E-mail addresses: [email protected] (S. Dawson),

[email protected] (D.E. Smith).

S. Dawson, D.E. Smith / Marine Geology 170 (2000) 69±7970

Fig. 1. Geomorphological and borehole location map of lower Strath Halladale, northern Sutherland. Inset shows the location of the study area

in northern Scotland.

Research by Smith et al. (1985) has established the

widespread accumulation of a distinctive horizon of

marine sand within Holocene coastal sediments in

eastern Scotland. This horizon was subsequently

interpreted as having been laid down by a tsunami

triggered by the Second Storegga Slide on the

continental slope off western Norway (Dawson et

al., 1988) This paper describes the ®rst occurrence

of the sand horizon outside the North Sea basin. The

sedimentology of this deposit is the focus of the

present paper.

2. Geological context

The coastline of northern Sutherland is intersected

by the northward draining river valleys. Strath

Halladale (Fig. 1) is one of the largest of these valleys

and appears to have been a major corridor for the

deposition of outwash material during the deglaciation

of the last Scottish ice sheet. Much of this material has

been eroded and redeposited by subsequent ¯uvial

action. At the mouth of the valley, in Melvich Bay,

granitic rocks of the western headland and ¯agstones

of Old Red Sandstone to the east form impressive

cliffs. A large boulder beach occurs at the western

extremity of the bay. At the eastern side a terraced

intertidal rock platform occurs.

The study area comprises the lower 3 km of

Strath Halladale, where the river ¯ows across a

wide ¯oodplain. Throughout this area, the river is

tidal and the ¯oodplain and saltings are frequently

inundated by spring tides. The present altitude of

the High Water Mark of Ordinary Spring Tides

(HWMOST) at Strath Halladale is 12.30 m OD

(Admiralty Tide Tables, 1996). The surface of the

¯oodplain declines consistently down-valley from

an altitude of 3.5 m above Kirkton before levelling

out beyond the roadbridge (Fig. 1), where it gradu-

ally merges with the modern saltings at ca. 2 m.

Towards the mouth of the Halladale River, the

vegetated saltings have an upper surface at 2.11±

2.61 m OD and a lower surface of 1.95±2.08 m OD.

The surfaces are ¯ooded by spring tides. At the edge

of the saltings, a small bluff overlooks sand¯ats,

which are exposed during the tidal cycle at between

1.74 and 1.90 m OD.

3. Methodology

Sediments have been traced across the ¯oor of

Strath Halladale using an Eijkelkamp gouge of 2 cm

diameter to determine the overall sedimentary

sequences and inter-relationships. Samples for labora-

tory analyses were collected using a 50 mm diameter

Stitz piston corer, which provided undisturbed cores

up to 1.3 m long. In the laboratory, a photographic

record of each core was taken before detailed

stratigraphical descriptions were made, followed by

sub-sampling for microfossil and particle size analy-

sis. Preparation for diatom analysis followed well-

established techniques (Barber and Haworth, 1981)

and a minimum count of 300 valves was made

where possible. A Malvern Mastersizer 2600 involving

laser diffraction spectroscopy was used to determine

particle size of the minerogenic sediments. The

mean particle size and standard deviation were

calculated using Malvern software. Radiocarbon

dating was carried out at Beta Analytic, Miami.

Table 1 lists the dates obtained, calibrations use

Calib 4 according to the method of Stuiver and

Reimer (1993). All dates referred to in the text are

quoted in radiocarbon years BP.

S. Dawson, D.E. Smith / Marine Geology 170 (2000) 69±79 71

Table 1

Radiocarbon dates from Strath Halladale. Ages in conventional radiocarbon years (1s) and calibrated ages (cal BC, 2s)

Laboratory code 14C age ^ 1s BP Calibrated age

(cal BC)

Altitude

(m OD)

Depth

(m)

Material dated

Beta-105030 (AMS) 7290 ^ 50 6228±6054 24.25 7.19 Peat

6043±6029

Beta-105031 (AMS) 7590 ^ 50 6507±6373 24.98 7.92 Peat

6364±6346

6311±6260

S.

Da

wso

n,

D.E

.S

mith

/M

arin

eG

eolo

gy

170

(2000)

69

±79

72

Fig. 2. Section along lower Strath Halladale showing the sedimentary sequence examined.

4. Stratigraphy

The sediments have been classi®ed into two major

facies groups based on their sedimentary characteris-

tics. Group 1 facies incorporate the underlying and

overlying sedimentary suite, and group 2 facies

incorporate the distinctive suite of sediments within

the stratigraphy of Strath Halladale.

Group 1 facies. The facies in group 1 incorporate

intercalated peats and clastic sediments with graded

transitional facies, which represent sediments asso-

ciated with long-term sea surface change (Dawson,

1999). Representative stratigraphical pro®les from

north to south and from east to west within the valley

are shown in Figs. 2 and 3. Organic sediments both

under- and overlie the depositional unit under

investigation. The overlying peats grade into a black

organic gyttja, which, from an analysis of the micro-

fossils, indicates deposition within a shallow tidal

lagoon (Dawson, 1999). This quiet water sedimenta-

tion and distinct organic facies is well suited to the

identi®cation and preservation of a contrasting sediment

body accumulated during a high-energy event.

Group 2 facies. Detailed stratigraphical analyses

were restricted to the sediments retrieved from core

SH 2, the deepest borehole undertaken in the valley.

Examination of Fig. 4 shows in detail the major

elements of the distinctive suite of sub-units contained

within the sediment. The sediment succession starts

with a pronounced erosional unconformity with the

underlying organic deposit. This is overlain by

alternating sand layers of varying particle size, and

redeposited organic material (mostly eroded peat),

from the underlying organic deposits. Some of the


Fig. 3. Cross-valley stratigraphic transect of lower Strath Halladale.


Fig. 4. Detailed stratigraphy of coarser unit within the sediment sequence of SH 2 and the mean particle size pro®le in microns at 1 cm

contiguous intervals. Fining upwards sequences are shown to the right of the pro®le.

sand layers are graded, whilst others are unsorted. The

organic horizons contain clasts, twigs, stems and

macrofossils as well as other plant detritus, which

are often found in a chaotic matrix of silt, clay and

sands. The base of the sedimentary succession is

erosive, whereas the upper boundary with the over-

lying shelly organic material becomes ®ner and

more gradual. The sediments can be divided into

®ve sub-facies:

1. Graded sands (sub-facies a). These are composed

of very coarse sand with ®ne gravel at the base,

grading upwards to medium and often ®ne grey

sand. The ®ne sand often has detrital plant material

present with occasional small twigs.

2. Massive sand (sub-facies b). The massive sand is

generally coarse to medium with de®ned bound-

aries. The unit is thinner than the graded beds

and has no apparent internal structure.

3. Organic inclusions (sub-facies c). This unit is

composed of a variety of materials, with clasts of

different origin including peat, silt, undifferentiated

organic matter, sand, gravel, twigs and plant

matter. Sand and silt laminae are also present.

Typically, the twigs are of Betula sp. and approxi-

mately 1±2 cm in length. Where present they are

orientated parallel to the silt and sand laminae.

4. Organic detritus (sub-facies d). Subfacies d resem-

bles subunit c and the boundary between them is

transitional. The layer is characterised by ®ner

plant debris, twigs and detrital matter. The minero-

genic fraction of the unit is typically ®ne sand.

5. Light grey silt (sub-facies e). Grey silt laminae are

often present lying stratigraphically above the

organic detritus (sub-facies d).

4.1. Microfossils

The sedimentary facies was examined for diatoms

and foraminifera. While no foraminifera were found

(J. Wells, pers. commun), diatom species were present

in small numbers within the ®ner sands and clays of

the intercalating sequence. In view of the small

number of individuals present, no viable counts

were possible. Identi®able species include a range of

marine and brackish species, including Paralia

sulcata, Cocconeis scutellum, Grammatophora

oceanica, Rhaphoneis surirella, Diploneis smithii,

Diploneis interrupta and Auliscus sculptus. In

addition, there are many freshwater species present,

identi®able only by their intact central areas, such as

Pinnularia sp. and Fragilaria construens species.

Diatom valves were often broken and therefore,

identi®cation was dif®cult. A full count was not

undertaken.

Table 2 details the main taxa present, together with

the total number of valves identi®ed. One sample was

taken from the ®ner clastic sediments within the unit,

and discloses a complex suite of diatoms. This is

dominated by the polyhalobous planktonic Paralia

sulcata, the valves of which are of a very broken

and fragmentary nature. Other fully marine indicators

are present including Rhaphoneis surirella, a sand-¯at

living benthon (Vos and De Wolf, 1993). The sample

also contains a range of mesohalobous and oligo-

halobous species including Diploneis and Fragilaria

species. The assemblage contains a range of species

from many differing habitats within the coastal zone,

from fully marine subtidal to intertidal sand¯at and

supratidal dwelling species, and has a clear allochtho-

nous component.

4.2. Particle size analysis

The entire sediment sequence was also analysed for

particle size and comprised 74 cm of material, which

was sampled contiguously with 1 cm thick samples


Table 2

Diatom species and total number of valves (24.25 to 25.00 m OD)

Diatom species Total number

Paralia sulcata (broken and eroded) 135

Grammatophora oceanica 40

Auliscus sculptus 7

Rhaponeis surirella 12

Cocconeis scutellum 22

Diploneis interrupta 17

Diploneis ovalis 12

Navicula forcipata 4

Diploneis smithii 9

Navicula abrupta 5

Navicula pusilla 25

Pinnularia sp. 34

Fragilaria construens 36

Epithemia sp. 6

Total no. of valves 364

and the results are shown in Fig. 4. Mean particle size

is determined in microns and discloses a multi-modal

particle size distribution. From the base of the

sequence upward, variation in mean particle size is

complex. However, certain trends are identi®able.

The sequence is characterised by several ®ning-

upward sequences. This can be determined both

visually, from inspection of the detailed stratigraphy,

and from the trend of mean particle size. Five indivi-

dual coarse±®ne suites can be seen, with a range of

particle sizes from ca. 500 to 40 mm. At a depth of

765±769 cm, a unit of unsorted sand occurs, and

particle size through this unit exhibits no change. In

addition to the individual ®ning-upwards sequences,

the overall trend of mean particle size throughout the

unit is from predominantly coarse at the base, at

792 cm depth to ®ne at the top, at 719 cm depth.

4.3. Chronology

Radiocarbon dates on samples at the upper and

lower contacts of the deposit have been determined

from borehole SH 2. The dates were obtained by the

Accelerator Mass Spectrometer method. The date

obtained on organic deposits immediately beneath

the deposit is 7590 ^ 50 14C yr BP (24.98 m OD).

and the overlying organic sediment is dated at

7290 ^ 50 14C yr BP (24.25 m OD), calibrated ages

6507±6260 cal BC and 6228±6029 cal BC, respec-

tively. The ®rst date is thought to represent a maxi-

mum age, because the underlying peat surface, from

which it was taken, appears to have been eroded from

the sharp contact and presence of peat intraclasts in

the sand above. The upper date is thought to be a more

accurate re¯ection of the age of the event in the

valley, since a more gradual change occurs across

the upper boundary with no apparent erosion.

5. Facies inter-relationships

The presence of an erosional unconformity at the

base of group 2 facies implies that the time the deposit

took to accumulate was less than the span of the radio-

carbon dates, and that some of the underlying deposit

has been removed. The unit of graded sand, which

overlies the unconformity, suggests rapid deposition

from a suspended state. The presence of ripup clasts

of peat and gyttja indicate high-energy erosive

processes. The greatest accumulation of organic clasts

is concentrated towards the lower parts of the group 2

facies re¯ecting the initial erosion of the underlying

deposits. The presence of alternating graded sand beds

and organic facies throughout the sedimentary succes-

sion possibly indicates several pulses of erosion and

re-deposition with the decreases in grain size indicat-

ing the decreasing velocity of each pulse of erosion

and a pattern of episodic deposition. Thus, the sand

beds re¯ect higher energy conditions and the organic

facies and silt lamineae re¯ect intervals of deposition

from suspension under quieter conditions.

6. Discussion

Several processes can be considered as responsible

for the deposition of the sedimentary sequence. These

include: ¯ooding by the river, slumping, possible

long-term sea surface change, storm surge or tsunami

inundation. The overall form of the deposits precludes

the effects of ¯uvial ¯ooding and possible slumping

from the valley sides. The presence, however frag-

mentary, of marine microfossils and the geometry of

the base of the deposit suggest deposition under

marine conditions. The deposits are not attributed to

a progressive secular marine transgression into the

valley because they contrast sharply with the lagoonal

sediments both under and overlying them. A storm

surge hypothesis is precluded because only one

extreme event has been identi®ed within the Holocene

sequence and many storms have impacted the north

coast of Scotland over the last century with no apparent

trace within the stratigraphic record.

It is believed that the deposits incorporating the

alternating coarse to ®ne sedimentary suites and the

intercalated organic facies represent a deposit of a

high-energy event. Several factors support this view.

Firstly, the diatoms, in contrast to those of other layers

analysed, are generally eroded with up to 90% of the

pennate species broken and many centric species

damaged. Secondly, there is evidence that the basal

peat was eroded as the initial coarse sand accumulated.

At borehole SH 2, fragments of peat occur in the

lower part of the grey silty ®ne sand and at all bore-

holes, the basal contact is particularly sharp in appear-

ance. Thirdly, the sand unit rises sharply up-valley

from between 24.98 (borehole SH 2) to ca. 20.50 m


between boreholes SH 13 and SH 12, a rise of ca.

4.5 m for the base of the deposit over a distance of

700 m. Indeed, the rise of 4.5 m is actually a mini-

mum, since the layer is apparently still descending

seaward at borehole SH 2. Fourthly, the radiocarbon

dates imply a relatively short period of deposition.

The sequence probably accumulated closer to the

upper date of 7290 ^ 50 BP (6228±6029 cal BC)

and the calibrated dates at 2s almost overlap. Taken

together the microfossil, stratigraphical and radio-

carbon evidence supports relatively rapid accumulation

under high-energy conditions.

The sedimentary signature within the stratigraphy

of the Strath Halladale valley is thought to be

representative of the passage of a tsunami generated

by the Second Storegga Slide, dated elsewhere at

between ca. 7400 and ca. 6900 radiocarbon years

BP. (Dawson et al., 1988). Where the deposit is

found, the base of the sequence is normally marked

by an erosional unconformity. The sand bed, which

overlies the unconformity, is graded, indicative of

rapid deposition of sand settling out from the tsunami

waves. The organic clasts in subunits c and d are

probably indicative of erosion of both the underlying

organic material as well as the presence of organic

detritus in the vicinity. The presence of sub-unit d

(overlying b and c) re¯ects the settling out of the

®ner sands and detritus as the wave energy dissipated

and the presence of silt laminae above the organic

horizons re¯ects the ®nest material settling out of

suspension. Within the sedimentary sequence at site

SH 2 the presence of ®ve units of coarse to ®ne

sediments and associated organic and silt sub-units

implies several pulses of erosion and deposition,

with the alternation between sand and organic fractions

suggesting an episodic pattern of deposition. In

general, the sand units record higher energy events

and the ®ner laminated units (incorporating the

organic fractions) record intervals of deposition

from suspension under possibly quieter conditions.

Diatom evidence, although fragmentary, indicates a

fairly disturbed accumulation of the deposit with all

habitats represented from open marine, subtidal

mud¯ats, intertidal mud¯ats, saltings and freshwater

environments. This is also characteristic of tsunami

sediments in that the waves will inundate a whole

range of habitats and thus produce a fairly chaotic

assemblage (Dawson et al., 1996; Hemphill-Haley,

1996; Goff et al., 2000). This is in marked contrast

with marine sediments accumulating under conditions

of secular, relative sea level rise, in which gradual

transitions are often noted from freshwater, through

brackish to fully marine assemblages (e.g. Smith et

al., 1992; Dawson and Smith, 1997).

The particle size analysis results (Fig. 4) disclose

striking similarities with those from study of the

sedimentology of contemporary tsunami deposits,

for example those from Indonesia (Shi, 1995), in

showing an upward progression of variations in

multi-modal distribution as well as an upwards ®ning

of all modal sub-populations within the sediment.

This lends further support for a tsunami hypothesis

for the Strath Halladale sedimentary sequence.

Sedimentological studies of recent tsunamis show a

very complex pattern of erosion and deposition (Yeh

et al., 1993; Shi, 1995). Incoming tsunami waves may

erode and transport material landwards, and the back-

wash carries material seawards (Minoura and Nakaya,

1991). Therefore, the sedimentary sequences are often

highly localised due to the local bathymetry inducing

complex hydrodynamic conditions. Nevertheless, the

sedimentary units are similar in Scotland and Norway

(Dawson et al.,1993; Bondevik, 1996) and in Indonesia

(Yeh et al., 1993). The rise in the height of the

deposit up-valley of between ca. 25 and 20.5 m over

a distance of 800 m is likely to have been accomplished

by a ¯ow of water inland, which reached greater

altitudes. Circumstantially, the age of the Strath

Halladale valley deposit is similar in age, microfossil

content, preservation and stratigraphical position to

similar sand layers described from a number of coastal

sites in eastern Scotland (e.g. Smith et al., 1980, 1983,

1985, 1999; Smith and Cullingford, 1985; Dawson

and Smith, 1997) interpreted as having been laid

down following the Second Storegga Slide tsunami

(Dawson et al., 1988).

In accord with recent evidence from Norway, in

which the time of year the tsunami is thought to

have struck the coastline has been alluded to from

macrofossil and faunal evidence, further re®ning of

the timing of the event has been possible from Strath

Halladale. Within the subunit c (organic clasts) a

macrofossil of Prunus avium L. (wild cherry) has

been identi®ed (M Field, pers. commun.). The fruit

occurs commonly on the trees in the Autumn time (late

September 2 October) and although its provenance in


uncertain due to a lack of additional macrofossils, it

gives added support to the autumn age for the event

determined by Bondevik et al. (1997a,b). Within a

Norwegian Lake basin, ®sh bones deposited with the

tsunami sediments were attributed to the Autumn

based on their size.

Only a minimum value can be given for the run-up

of the tsunami at Strath Halladale. This is due to the

selective preservation of the tsunami deposits within

the valley; the fact that lower seaward deposits may

occur and because the sedimentary signature may not

represent the ®nal elevation attained by the tsunami

waves. Nevertheless, the evidence presented suggests

at least a 4.5 m run-up (even accounting for compac-

tion of the underlying peat, which is calculated to

22 cm the run-up is in the vicinity of 4 m) for the

event in Strath Halladale, as determined from the

stratigraphic extent of the deposit within the Strath

Halladale valley. This is currently greater than the

value for run-up from available numerical models

(Harbitz, 1991), although these use relatively simple

bathymetric information. The presence of tsunami

deposits attributed to the Second Storegga Slide in

Strath Halladale provides the ®rst evidence for the

event outside the North Sea basin, and the highest

minimum run-up of this tsunami recorded to date,

despite the possible sheltering effect of the Orkney

and Shetland Islands located immediately in the

path of an incoming tsunami from the Norwegian

continental slope. It is possible that the magnitude

of the run-up may re¯ect particular local conditions,

including the point on the tidal cycle when the

tsunami struck.

6.1. Tsunami inundation into a shallow lagoonal and

estuarine environment

Studies of recent tsunamis exhibit a highly complex

pattern of erosion and deposition (Dawson, 1994; Shi,

1995; Sato et al., 1995, 1996). Processes of tsunami

backwash are poorly understood (Dawson, 1994), but

are thought to re¯ect the redeposition of much of

the eroded clasts and sand sheets. The deposits

attributable to tsunami inundation range from single

sand sheets of a few centimetres in thickness (e.g.

Reinhardt and Bourgeois, 1989; Minoura and Nakaya,

1991) to multiple graded sand units and intercalated

organic facies (e.g. Shi, 1995; Bondevik et al., 1997a,b)

and even boulder deposition (Dawson, 1996). This

re¯ects, in the main, the site speci®c antecedent

conditions and the hydrodynamic nature of the

tsunami to variable offshore bathymetry. Neverthe-

less, tsunami inundation into quiet-water lagoonal

sedimentation holds great potential for preservation

of the tsunami deposits and may lead to the deposition

of a sedimentary succession, which can be observed in

many other localities, both in other sites around

Scotland and further a®eld, for example in coastal

lagoonal deposits and isolation basins at sites in

western Norway (Bondevik et al., 1997a,b).

7. Conclusions

Detailed analysis of a sedimentary sequence within

deposits attributed to middle Holocene lagoonal

conditions in Strath Halladale, northern Sutherland,

reveals the presence of a distinctive sedimentary

suite, which contrasts strongly with the enclosing

sediments. The sediments have been classi®ed into

®ve predominant facies, and have been attributed to

a tsunami, probably triggered by the Second Storegga

Slide dated to ca. 7100 radiocarbon years BP. The

main characteristics of the deposit are that it is under-

lain by an erosional unconformity with an overlying

distinctive graded or poorly sorted medium to

coarse sand, which contain eroded organic sediments,

redeposited gyttja, plant and twig fragments eroded

from the underlying sediments. A sequence of graded

sand from coarse to ®ne lies stratigraphically above

the redeposited organic fragments. Within the Halladale

valley, the coarse to ®ne sequences are repeated and

up to four ®ning upwards sequences are present, and

®ne silts are characteristic immediately overlying the

®ner sand sediments.

The presence of a deposit of the Second Storegga

Slide tsunami in the Strath Halladale valley taken with

the evidence of the event elsewhere demonstrates that

the tsunami not only affected the low-lying eastern

coast of mainland Scotland but also the coastline of

the Pentland Firth.

Acknowledgements

The authors are grateful to Lucy Holloway, James

Wells and Anne de la Vega for assistance with the


®eldwork and to Mike Field for identifying the

macrofossils. Thanks are extended to Kirsty Handley

and Erica Milwain for cartographic assistance.

Roland Gehrels and James Goff are thanked for

their constructive advice. The research was partially

funded by the European Union under Contract

EV5C-CT93-0266 and radiocarbon dates were

funded by the Centre for Quaternary Science,

Coventry University. This work is a contribution to

IGCP 367 Rapid coastal changes during the Late

Quaternary.

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the sedimentology of middle holocene tsunami facies in northern sutherland, scotland, uk

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