High Cliffs Research Articles

Quaternary carbonate-rocky talus slope successions (Eastern Alps, Austria): sedimentary facies and facies architecture

Quaternary carbonate-lithic talus slope successions of the Eastern Alps record an overall correlation between prevalent sedimentary facies, depositional geometry, and geomorphic maturity of the slope. After exposure of high cliffs by deglaciation or rocksliding, a low-dipping immature talus dominated by unsorted rockfalls initially accumulates. With progressive talus buildup, slope segments of different dips develop. Concomitantly, prevalent depositional processes change to grain flows and sorted rockfalls in the proximal, steep-dipping (35°–30°) slope segment, while deposits of cohesive debris-flows, ephemeral fluid flows and larger rockfalls prevail in the distal, lower-dipping slope segment. In mature talus deposystems, the proximal slope succession overlies the lower-dipping package of the distal slope along a thin ‘downlap interval’. Immediately after cliff exposure by deglaciation or rocksliding, talus may aggrade at rates of up to a few tens of meters per 1,000 years, but the accumulation rate slows strongly with progressive maturity of slopes.

Rates and Trends of Coastal Change in California and the Regional Behavior of the Beach and Cliff System

The U.S. Geological Survey (USGS) recently completed an analysis of shoreline change and cliff retreat along the California coast. This is the first regional, systematic measurement of coastal change conducted for the West Coast. Long-term (∼120 y) and short-term (∼25 y) shoreline change rates were calculated for more than 750 km of coastline, and 70 year cliff-retreat rates were generated for 350 km of coast. Results show that 40% of California's beaches were eroding in the long term. This number increased to 66% in the short term, indicating that many beaches have shifted toward a state of chronic erosion. The statewide average net shoreline change rates for the long and short term were 0.2 m/y and −0.2 m/y, respectively. The long-term accretional signal is likely related to large coastal engineering projects in some parts of the state and to large fluxes of sediment from rivers in other areas. The cliff-retreat assessment yielded a statewide average of −0.3 m/y. It was found that Northern California has the highest overall retreat rates, which are influenced by erosion hot spots associated with large coastal landslides and slumps. The databases established as part of the shoreline change and cliff-retreat analyses were further investigated to examine the dynamics of the beach/cliff system. A correlation analysis identified a strong relationship between the geomorphology of the coast and the behavior of the beach/cliff system. Areas of high-relief coast show negative correlations, indicating that higher rates of cliff retreat correlate with lower rates of shoreline erosion. In contrast, low-to moderate-relief coasts show strong positive correlations, wherein areas of high shoreline change correspond to areas of high cliff retreat.

Sun and landscape orientation in adult and juvenile sandhoppers Orchestoidea tuberculata (Amphipoda, Talitridae) from two beaches in south central Chile

AbstractThe behaviour of a talitrid amphipod, Orchestoidea tuberculata Nicolet 1849, was investigated for populations inhabiting two exposed sandy beaches in south central Chile to evaluate orientation capabilities with respect to sun azimuthal changes and landscape. The study beaches (Calfuco and La Misión) were backed by high cliffs but differed in shoreline orientation. Under test conditions of dry substrate, both populations oriented seawards using celestial cues when landscape vision was screened off and showed a higher concentration seawards when they could see the landscape suggesting additive effects of these cues. The absence of a phototactic response to the sun implies the involvement of an inner circadian clock, as the experiments were conducted at different times of the day. The distribution of juveniles was more concentrated than adults in the trials, a result in accordance with their tendency to occupy a zone located closer to the water than adults. Our results suggest that the Calfuco population was oriented to its shoreline, while animals at La Misión tended to deviate from the expected direction and their distribution was more scattered. This observed difference between the populations may be related to the higher human impact on the latter beach, which was more intensively used for recreation and periodically cleaned, removing the wrack. The comparison of results on orientation of O. tuberculata with those of different sandhopper species contributes new phylogenetic insight concerning this important adaptation. This study not only represents an extension of contemporary knowledge of behavioural adaptations of beach amphipods to coasts differing geographically and ecologically, but also analyses orientation in a southern Pacific species of talitrid amphipod for the first time.

Modelling the processes of cliff-top erosion and deposition under extreme storm waves

At exposed sites on the deep water coasts of the British Isles, cliff-top storm deposits (CTSDs) occur on cliffs at a variety of elevations above sea level and may occasionally reach up to 50 m above sea level. Time-series field mapping of CTSDs has demonstrated their formation over the historical period and their continued modification during major past storms. This paper seeks to clarify the morphogenetic context of CTSDs, model the wave conditions and forces encountered at the cliff-face and cliff-top platform and propose mechanisms to link wave processes to cliff-face quarrying and landwards cliff-top transport of quarried blocks to deposition zones at the rear of the cliff-top platform. We report on wave-tank experiments using scaled cliff and wave conditions from a cliff in the Shetland Islands to focus on three situations: incident waves lower than the cliff edge height; at the same height as the cliff edge height; and higher than the cliff edge height. The modelling suggests that steep waves of 10 m and above impacting on a 15 m high cliff will result in impact pressures sufficient to promote crack propagation, block detachment and lifting of large blocks. Large, but not necessarily steep, waves of the same height as the cliff edge produce sufficient impact pressures and water flow over the cliff edge and platform to entrain blocks, transport and deposit them on the cliff-top. Where cliff-top height is below wave crest elevation “green water” bore flow occurs, sufficient to force rotation or lifting of blocks out of cliff-top and cliff-top platform ‘sockets’. High flow velocities rapidly accelerate and transport blocks inland until the flow attenuation results in deposition of blocks at the limit of run-up. The model results provide a good explanatory framework to account for the quarrying of the upper part of the cliff-face and cliff-top platform under storm wave conditions and provide an insight into the exceptional velocities experienced over the cliff-top platform under bore flow conditions. The modelling results show that extreme storm waves are capable of quarrying, transporting and depositing large blocks at altitude and significant distances inland and so present serious questions about the use of such deposits as diagnostic of palaeo-tsunami.

Gravelly Gilbert-type fan delta on the Conway Coast, New Zealand: Foreset depositional processes and clast imbrications

Quaternary Gilbert-style fan deltas of the Conway Coast, New Zealand, are formed and exposed by the continuing uplift and erosion of the Hawkswood Range due to transpression associated with the modern New Zealand plate boundary. The fan deltas are exposed in 50–70 m high cliffs and crop out for over 5 km along the coast and up to 2 km inland. Depositional processes on the foresets were dominated by sediment gravity flows originating from hyperpycnal river flow and gravity induced slumps. Slumps may originate at any depth on the fan delta foreset and are common in the deposits. Foreset beds are interpreted as the deposits of sediment gravity flows with preserved foreset beds that are preserving normally graded, inversely graded or massive, and change abruptly laterally and down slope. Gravity induced slumps are the dominant mode of deposition on the foresets along the Conway Coast and presumably all Gilbert-type fan deltas. This study concludes that the sediment gravity flows developed basal traction carpets as evidenced by the regular appearance of ∼ 25° imbricated clasts in nearly all foreset beds. Behind slump deposits, there is a strong zone of ‘backstacking’ clast fabrics that prograde upslope into backset beds. These clast fabrics provide information about downslope slumps. Excellent exposures of distal foreset and nearshore marine deposits show the dynamic interface within a fan delta complex.

Extensive methane-derived authigenic carbonates in the Irish Sea

Extensive areas of methane-derived authigenic carbonate (MDAC) have been mapped in the Irish Sea. In the Irish Sector, 23 seabed mounds associated with the Codling Fault Zone were identified by multi-beam echo sounder mapping. Inspection by ROV-mounted video showed that these mounds are rocky features rising 5–10 m above the normal seabed; sampling showed that they are comprised of quartz grains bound together by carbonate cement, probably MDAC. Two separate locations have been mapped in the UK Sector. At Texel 11, seabed mounds and a 6–8 m high cliff were mapped geophysically (MBES, SSS and seismic profiler surveys). Video surveys showed that both the mounds and the cliff are rocky reefs colonised by a prolific fauna. Samples proved to be carbonate-cemented sediments, and carbon isotope analysis (δ13C −41 to −46% PDB) showed that the cement was MDAC. Similar surveys of the Holden’s Reefs area proved the presence of similar rocky reefs which are also cemented by MDAC. The total area covered by these two MDAC occurrences is estimated to be >500,000 m2. These MDAC occurrences are comparable in nature and formation to the ‘bubbling reefs’ of the Kattegat. As the bubbling reefs are “seabed features formed by leaking gas”, one of the marine habitats identified by the European Commission’s Habitats Directive as being sensitive and worthy of protection, it is suggested that the Irish Sea carbonate reefs should also be considered as special habitats.

Sedimentary processes over an intertidal flat: A field investigation at Hythe flats, Southampton Water (UK)

The sedimentary processes acting over an intertidal flat (Hythe, UK) located in Southampton Water, Hampshire, UK are investigated on the basis of hydrodynamic, morphological and sediment transport field measurements. Bed level changes, patterns of suspended sediment transport and shell movement over the tidal flats were examined in order to identify sediment transport pathways and salt marsh–mudflat morphological changes. Overall, sediment transport patterns at Hythe can be described in terms of suspended sediment and bedload-shell transport. The hydrodynamic complexity of the tidal flow over the flats determines the patterns of suspended sediments transport. During the young flood phase, tidal currents present a SW orientation (shoreward). About 1 h into the flood, a change occurs and the currents start flowing in a SE direction (estuary mouthward). This veering of the tidal current controls the hydrodynamic pattern over the mudflat inducing sediment transport towards the estuary mouth. Conversely, shell tracer experiment showed a net landward movement. Shells are transported over the mudflat, deposited at the base of the cliff, and eventually transported over the salt marsh where they form extensive chernier deposits. Shell transport rates can reach up to 0.7 m/tide over the upper mudflat. Shell movement over the salt marsh (on cheniers) occurred only during storms (up to 3 m in a storm event). Shell-induced erosion can become an important parameter on morphological changes of a coastal area. Shell transport and deposition over the salt marsh surface can contribute to vegetation deterioration, as shell deposits migrate over the marsh surface. As a result, the seaward limit of the salt marsh showed deteriorated vegetation, which leads to scouring and consequent surface lowering. In terms of bed level changes, no seasonal pattern was observed. A relationship between mudflat bed erosion and cliff retreat is suggested. During periods of high cliff erosion there was a tendency for the mudflats to be stable and, conversely, mudflat bed erosion was greatest when cliff retreat rates were lowest. Hence, morphological characteristics of Hythe intertidal area appear to be controlled by a combination of prevailing hydrodynamic conditions and shell transport over the salt marsh.

ILLITE/SMECTITE CLAYS PRESERVING POROSITY AT DEPTH IN LOWER PERMIAN RESERVOIRS, NORTHERN PERTH BASIN

The appraisal well Hovea–2, drilled in July 2002, was the first well in the onshore Perth Basin to discover commercial volumes of gas in sandstone reservoirs of the Artinskian (Early Permian) High Cliff Sandstone sealed beneath basal shales and siltstones of the Irwin River Coal Measures. A drill stem test in this formation, in the interval 2,370–419 mMDRT (measured depth below rotary table), flowed gas to surface at 16.5 MMcfd. Thereafter, the High Cliff Sandstone became an important play for exploration in the basin; however, no additional discoveries have been made in this reservoir, even though it has been tested in another seven wells (Jingemia–1, Eremia–1, Kunzia–1, Corybas–1, Yardarino–6, Hakia–2 and Bunjong–1).In Corybas–1, drilled in 2005, this reservoir was found to be water bearing, but an 18 m core was taken within the topmost High Cliff Sandstone. This core provided important insights into the fluvial depositional environment of these sands. Importantly, porosity and permeability are highly variable within the reservoir, with some coarser grained beds retaining anomalously high porosity and permeability due to the coating of constituent quartz grains by illite/smectite that inhibited late stage quartz overgrowth. Study of this core along with core from overlying Irwin River Coal Measures indicates that there may be some facies control on the presence of the grain-coating clays in the High Cliff Sandstone, and that the fluvial to tidal facies are more likely to be an effective petroleum reservoir than the overlying fluvial/alluvial facies. This reservoir is the primary objective in the upcoming exploration wells Beharra Springs Deep–1 and Drakea–1, to be drilled in 2007.

Space and Place for BASE: On the Evolution of a BASE‐Jumping Attraction Image

BASE jumping is an extreme sport activity that employs rare natural or man‐made resources from where the participants can legally leap and perform a free flight before landing on the ground, assisted by opening their parachute canopies at the last possible moment. The 1000‐metre high Kjerag Cliff in Lysefjord, Norway was first used for this sport in 1994. Since then, it has achieved a position as a “Mecca” for BASE jumpers worldwide, resulting in increased traffic of BASE jumpers and observers to the area. This article discusses how the image of this attraction has evolved. Data were collected from documents, printed sources, videos, and mainly from interviews with participants and central providers of services and support. The strong image that has emerged is built upon the exciting experiences of participants and observers, the paradoxical effects of accidents and fatalities, the media, and the strong impressions provided by watching this wild nature. A key component is the communication within the BASE‐jumping community by word of mouth, e‐mail, pictures, and amateur video recordings.

50-Million-Year-Long Record of Glacial to Postglacial Marine Environments Preserved in a Carboniferous-Lower Permian Graben, Northern Perth Basin, Western Australia

Abstract The Perth Basin is an intracratonic rift in Western Australia and contains a Carboniferous to Cretaceous infill in excess of 12 km thick. Some 2 km of mid-Carboniferous to Lower Permian glacially influenced marine strata spanning the Serpukhovian to Kungurian (about 50 My), form one of the longest late Paleozoic cold-climate successions preserved anywhere in Gondwana and record the transition from full glacial to postglacial conditions at high (70°) paleolatitudes. The great thickness of the succession reflects an abundant supply of glaciclastic sediment from the adjacent ice-covered Yilgarn Craton and continued subsidence along the Darling–Urella fault system. The oldest part of the basin fill comprises a 1.5-km-thick succession of massive and laminated marine mudstones with striated dropstones (Nangetty Formation) deposited in a fiord-like environment from plumes of suspended sediment, dilute turbidity currents, and icebergs. Meltwater inputs are recorded by erosionally based multistory channels filled with coarse-grained gravity-flow facies (Wicherina Member) deposited on a fan delta along the steep, faulted basin margin. The Nangetty Formation passes upward into a regressive succession of postglacial mudstones (Holmwood Shale) with bioclastic calcarenites and marine macrofossils, capped by sandstone and mudstone facies (High Cliff Sandstone) deposited in a storm-influenced inner shelf setting on the outer margins of coalesced fan deltas along the basin margin. The overlying Irwin River Coal Measures contain a flora that indicates colonization of fan deltas and the Yilgarn Craton by ferns and lycopods. An overlying thick transgressive shale with ice-rafted debris (Carynginia Formation) records renewed subsidence but continuing seasonally cool climates where coarse debris was rafted by ice into a marine embayment. The sedimentology of the Perth Basin highlights the key role of glacial meltwaters in transporting coarse- and fine-grained clastic sediment to marine basins rather than direct glacial processes per se. The equivalent terrestrial record of glaciation and climate change across the Yilgarn Craton at this time is very limited.

High Cliff in the Upper Shirouma Daisekkei Valley, Northern Hida Range

High Cliff in the Upper Shirouma Daisekkei Valley, Northern Hida Range

Selection of Breeding Cliffs by Griffon VulturesGyps fulvusin Crete (Greece)

A multivariate analysis was carried out in order to investigate the most influential habitat variables and related features in the selection of breeding cliffs by the Griffon Vulture in Crete. The species was found nesting in mid-altitude areas, close to stock-raising units, on high limestone cliffs, which were also well protected against the prevailing winds of the island. A principal components analysis, which explained 53% of the total variance of the variables examined, differentiated Griffon Vulture colonies in relation to their isolation from other colonies, accessibility to humans and proximity to food resources. In addition, a stepwise discriminant function analysis between breeding and random cliffs included the height of the cliff, its substratum, the altitude, and the distance to the stock breeding unit in a model that successfully classified 97.1% of the nesting and 88.2% of the random cliffs. In comparison to continental regions the Griffon Vulture colonies in Crete were located on higher cliffs but at a lower altitude. This fact should be attributed to the species nesting on steep coastal cliffs close to the livestock's wintering areas.

Conservation status and community structure of cliff-nesting raptors and ravens on the Cape Peninsula, South Africa

We detail the sizes, spatial distributions and trends in nest site selection of cliff-nesting raptor and raven populations resident in the mountains of the Cape Peninsula, South Africa. We also assess the conservation value of these populations to inform the future management of the newly-established Table Mountain National Park (TMNP), and examine the structure and interrelations within the raptor community. The combined number, dispersion and density of nests (n = 96 nests, mean inter-nest distance = 0.59km, density = 30.0 pairs/100km2) are comparable with those of high-density raptor populations studied elsewhere in Africa and the world. Densities of Verreauxs' Eagle Aquila verreauxii (n = 2, 12.01km, 0.6 pairs/100km2, respectively) and Jackal Buzzard Buteo rufofuscus (n = 9, 4.63, 2.8 pairs/100km2), are low, Rock Kestrel Falco rupicolus (n = 44, 1.75km, 13.8 pairs/100km2) high and Peregrine Falcon Falco peregrinus (n = 19, 3.13km, 5.9 pairs/100km2) exceptional, relative to populations of the same or similar species in other areas. There are no comparable data for White-necked Raven Corvus albicollis (n = 22, 3.22km, 6.9 pairs/100km2). All species combined, and Peregrines in particular, significantly prefer high cliffs from the available habitat. Peregrines generally dominate the other species, may affect cliff site selection and dispersion in the rest of the community, and tend to locate their nests close to those of White-necked Ravens. Numbers of Verreauxs' Eagle are lower than recent historical levels, perhaps because key prey populations are depleted. Any future recovery of this large predator could subtly affect the entire assemblage. This cliff-nesting raptor community is a significant asset of the TMNP, and should be considered in management decisions taken in the Park, particularly those concerning the regulation of leisure activities in the vicinity of nesting areas.

Cliff-top stabilisation of the Military Road, Isle of Wight

This paper describes the development of the design for an innovative retaining structure built to support an existing highway on the Isle of Wight. At Afton Down on the south-west coast of the island the A3055 Military Road passes above high chalk cliffs. Continuing erosion at the toe of the cliffs led to the cliff edge receding to within 15 m of the highway. As a result options to maintain the road were investigated. A public inquiry ruled out realignment inland onto the adjacent downland, whilst measures to prevent erosion at the toe of the cliffs were unacceptable for environmental whilstcoastal management reasons. Consequently the road was kept open, with instrumentation installed to warn against failure of the cliff, and work began on the design of a scheme to maintain the road along its existing alignment. An environmental assessment was carried out to address the potential impacts of schemes on the adjacent downland, with the resulting arrangement of a tied retaining wall aiming to minimise these. Furthermore, outline methods for decommissioning the structure when it reaches the end of its serviceable life were identified. Planning permission was granted in 2002, and following a series of trials the scheme was constructed in 2003 and the road reopened to the public.

Geomorphological Features and Evolution of the Ensenada de Atacames (Provincia de Esmeraldas, Ecuador)

Along the north-Ecuadorian coast, characterized by high cliffs alternating with small plains in correspondence with river mouths, the Ensenada de Atacames, limited backwards by the Cordillera Costanera, consists mainly in a gently sloping surface falling between 3 and 10 m a.s.l., which was the site of an human settlement belonging to the “Atacames culture” (500 B.C.–1500 A.D.). This surface is interrupted seawards by a vertical cliff, subject to a rapid retreat. The pedo-stratigraphic study reveals it was built in a coastal brackish lagoon. The continental shelf facing Atacames is pointed out the presence of a carbonatic bank, remnant of an arrecife of late Pleistocene or early Holocene. As regard to the formation of the lagoon, one has to think to the genesis of a sandy barrier which isolated the waters of the Ensenada from the open sea. Since the Middle Holocene transgression is well known and sands are widely diffused on the carbonatic bank, one can infer that the genesis of the sandy barrier occurs because of their deposition and due to processes of littoral drift. The lagoon was probably formed just after the Holocene Climatic Optimum, by the development of a more and more stable sandy bar, which could have emerged around 3500 BP, during a recognized decrease of the sea level. After the colonization, the Atacames surface could become affected by erosional processes. Taking into consideration the present-day events, the most probable explication of the break of the external sandy barrier, which primed an erosional process, could have been the recurrence of strong ENSO (El Niñ o Southern Oscillation) events.

Short contribution: Marine erosion and archaeological landscapes: A case study of stone forts at cliff‐top locations in the Aran Islands, Ireland

AbstractTwo massively constructed stone forts exist on the edge of vertical coastal cliffs on the Aran Islands, Ireland. One of these, Dun Aonghusa, contains evidence of occupation that predates the main construction phases of the walls and broadly spans a time interval of 3300–2800 yr B.P. The other fort, Dun Duchathair, has been termed a promontory fort because its remaining wall crosses the neck of a small promontory marginal to the cliffs. Estimates of past rates of marine erosion in this part of Ireland may be made both by analogy with studies in other areas and comparison with present day rates of marine erosion. A working model for erosion rates of approximately 0.4 m of coastal recession per annum is suggested. By applying this rate to the cliffs of the Aran Islands, it can be shown that, assuming a construction date of approximately 2500 yr B.P. for these forts, they were originally built at a considerable distance from the coastline. Thus Dun Duchathair was not a promontory fort. The earliest recorded habitation at Dun Aonghusa, dated to the middle of the Bronze Age, was, therefore, at some distance inland and not on an exposed 70 m high cliff on the edge of the Atlantic Ocean. © 2004 Wiley Periodicals, Inc.

Syndepositional faulting in the Grès d'Annot Formation, SE France: high-resolution kinematic analysis and stratigraphic response to growth faulting

Abstract The presence of syndepositional reservoir scale faulting in the Grès d'Annot Formation adds an additional level of complexity in understanding the stratigraphic architecture of these, and potentially other, deep-water reservoir successions. A series of five synsedimentary faults have been characterized in relation to the high-resolution depositional framework of the Annot deep-water sandstone, faults that were active at the time of deposition of the Grès d'Annot, influencing both stratigraphic architecture and depositional processes. The five faults have normal throw, strike NE-SW (perpendicular to the regional palaeocurrent direction), and have maximum syndepositional throws of between 5 and 30m (sub-seismic-resolution scale). To understand the nature of the synsedimentary faulting, a high-resolution stratigraphic framework was developed from six vertical sedimentary sections measured along the 600m high cliff face, and from detailed correlations along photomosaic panels. Ten lithofacies have been identified and grouped into three different architectural elements that have been used as reference units for the high-resolution kinematic analysis. Syndepositional deformation of these architectural elements indicates that the faults had a polycyclic kinematic behaviour. In the hanging wall, abrupt pinchout of sandstone bodies and unusual local variations in sandstone texture also support the influence of faulting during deposition.

THE NORTHERN PERTH BASIN—FROM MARGINALLY PROSPECTIVE FOR GAS TO HIGHLY PROSPECTIVE FOR BOTH OIL AND GAS

Recent discoveries of gas in the Wagina Formation by Beharra Springs North–1, in the High Cliff Sandstone by Hovea–2, and of oil in the Dongara Sandstone by Hovea–1, Jingemia–1 and Eremia–1, have changed the perception of the northern Perth Basin from being marginally prospective for gas to one that is highly prospective for both oil and gas. Enhanced quality of 3D seismic over 2D, an analysis of regional gravity data, and in-house reservoir and source rock studies have all played a part in these discoveries. Hovea–2 is significant in that it flowed gas at commercial rates from the Lower Permian High Cliff Sandstone, the first well in the basin to do so from this reservoir. A program involving extensive additional 3D seismic and as many as six exploration wells is planned for 2004, offering the potential for further significant hydrocarbon discoveries.

Rafter beekeeping in Cambodia with Apis dorsata

In the UK, it can be difficult to explain to non-beekeepers the differences between honey bees, bumble bees and wasps, let alone complicating the matter further with the mention of solitary bees Visiting Asia adds a wholenew dimension to the equation with the opportunity to see several different species of honey bee. The thought of bees that build comb in the open air and protect it with a curtain of workers is totally alien to those who have only ever dealt with cavity-dwelling bees. Seeing the great colonies of the giant honey bees, Apis dorsata and Apis laboriosa, hanging from huge tree branches or extremely high cliffs is an experience that takes your breath away and is one that you never forget. Generally, these colonies are well out of reach of humans and the honey hunters have to take extreme measures to collect the honey. In Cambodia, we saw a colony that had been attracted to build its comb on a man-made rafter, set up at head height. This was another unforgettable experience and one that has not been recorded previously.

Planning for Shoreline Response to Spills in Arctic Environments

ABSTRACT The Arctic coasts present three unique shoreline types that are common in North America and Eurasia, but that are not found in lower latitudes or in the southern hemisphere: tundra cliffs, peat shorelines, and inundated low-land tundra. Tundra cliffs range in character from ice-rich exposures that are dominated by rapid thermo-erosional processes to high (10–15 meters) sediment-rich cliffs that may be eroded by slumping or basal sapping. One product of this rapid erosion of the tundra is to produce large volumes of peat and in many sections these form the dominant shore-zone material. In low-lying areas the flooding of the tundra has produced extremely complex shoreline configurations characterized by the elevated rims of patterned ground. These unique arctic shore types present different sets of challenges for shoreline cleanup and treatment and have been included in the U.S. marine oil spill response guide published in 2001 by API, NOAA, USCG, and USEPA and several specialized Arctic response manuals published recently by Environment Canada. A low-altitude aerial videotape survey in 2001 produced continuous images of the mainland and barrier island coasts of the Alaskan Beaufort and Chukchi Sea coasts from the Canadian border to Point Hope, used to map the shore types as part of a mapping project for the Minerals Management Service. The mapping revealed that the three arctic shoreline types are present on more than half (54 per cent) of the coast between the Canadian border and Point Hope.