Vertical Cliff Faces Research Articles

Origin, geomorphology and geoheritage potential of Australia’s longest coastal cliff lines

Two spectacular cliff lines occur along Australia’s south and west coasts: the Great Southern Scarp (new name) and the Zuytdorp Cliffs. Detailed measurements of their length show that they are exceptionally long and unusually continuous. The Great Southern Scarp is the southern edge of the Nullarbor Plain’s Bunda Plateau; it is cut into shallow marine sediments and extends for 820 km. Once a continuous sea-cliff, local uplift has isolated two sections from the ocean, so it now comprises the Bunda Cliffs (210 km of coastal cliff, 180 km of which is uninterrupted cliff line), Hampton Range (inland; 300 km), Baxter Cliffs (160 km of coastal cliff) and Wylie Scarp (inland; 160 km). The Zuytdorp Cliffs are coastal cliffs cut into eolianite, and extend for 210 km with an uninterrupted section of 120 km. The length of the Great Southern Scarp and the Zuytdorp Cliffs results from an unusual combination of circumstances. They are both composed of poorly jointed, relatively homogenous biogenic calcarenites, presented to high-energy ocean waves by regional uplift. The carbonates are sufficiently well cemented to maintain a steep vertical cliff face, but susceptible to disintegration under direct wave attack. Cliff retreat has been fairly uniform because of the broad spatial scale of both lithology and erosion. The arid climate, absence of nearby non-karstic catchments and karstic nature of the cliffs’ hinterlands has discouraged integrated drainage development, so no significant fluvial systems dissect the cliffs; this is a key factor in cliff edge preservation. In the case of the Great Southern Scarp, these processes have formed the longest continuous cliff line in Australia and probably the world. Referenced against criteria from Australia’s National Heritage List, the cliffs have potentially international/national levels of significance for the rarity of their scale, their demonstration of landscape evolution, and their spectacular beauty.KEY POINTSAustralia’s longest coastal cliffs, the Bunda (SA) and Zuytdorp (WA) cliffs, are equal in length (210 km, within defined confidence levels).The Bunda Cliffs are part of the Great Southern Scarp (new name), an 820 km-long feature of the Nullarbor Plain that also includes the coastal Baxter Cliffs (160 km in length) and two paleocoastal scarps.The unusual continuity of the cliff lines results from a landscape history specific to the Australian continent, and the Great Southern Scarp is likely to be unusual on a global scale.The Great Southern Scarp and the Zuytdorp Cliffs have potentially national and/or international levels significance for geoheritage values in the criteria of events and processes, rarity and aesthetics.

Locating Cave Entrances Using Lidar-Derived Local Relief Modeling

Lidar (Light detection and ranging) scanning has revolutionized our ability to locate geographic features on the earth’s surface, but there have been few studies that have addressed discovering caves using this technology. Almost all attempts to find caves using lidar imagery have focused on locating sinkholes that lead to underground cave systems. As archaeologists, our work in the Chiquibul Forest Reserve, a heavily forested area in western Belize, focuses on locating potential caves for investigation. Caves are an important part of Maya cultural heritage utilized by the ancient Maya people as ritual spaces. These sites contain large numbers of artifacts, architecture, and human remains, but are being looted at a rapid rate; therefore, our goal is to locate and investigate as many sites as possible during our field seasons. While some caves are entered via sinkholes, most are accessed via vertical cliff faces or are entered by dropping into small shafts. Using lidar-derived data, our goal was to locate and investigate not only sinkholes but other types of cave entrances using point cloud modeling. In this article, we describe our method for locating potential cave openings using local relief models that require only a working knowledge of relief visualization techniques. By using two pedestrian survey techniques, we confirmed a high rate of accuracy in locating cave entrances that varied in both size and morphology. Although 100% pedestrian survey coverage delivered the highest rate accuracy in cave detection, lidar image analyses proved to be expedient for meeting project goals when considering time and resource constraints.

A new aerial photogrammetric survey method for recording inaccessible rock art

This article presents a practical workflow that utilizes Unmanned Aerial Vehicle (UAV) based photogrammetric survey to contextualize large expanses of rock art distributed across the complex topography of an inaccessible cliff face. We demonstrate our proposed workflow through a case study of a collection of petroglyphs along a two kilometer stretch of limestone escarpment in the vicinity of the archaeological site of Quilcapampa in the Majes district of southern Peru (ca. AD 800-1500). Following a review of existing methods of petroglyph documentation and digital heritage reconstruction, we then present our workflow for using UAVs to create a precisely georeferenced registry of petroglyphs on a three-dimensional model of a vertical cliff face and compare these results to more traditional pedestrian survey. We close by outlining the value of this model for future geospatial analysis, site conservation and visualization, and public archaeology.

Calculating Lateral Frost Front Penetration in a Rapidly Retreating Cliff of Fine Sediments

An adapted version of the Stefan equation (CLIFFSE) was tested to predict lateral progression of the frost front into cohesive sediments that form coastal cliffs along the north shore of the maritime estuary and gulf of the St Lawrence River (Quebec, Canada). The equation was adapted to accommodate the influence of cliff erosion on lateral penetration of freezing and thawing into vertical cliff faces. As the cliff erodes, freezing and thawing are initiated from the newly revealed surface. Frost progression and erosion were measured with an automated thermal erosion pin system. Measured observations agreed with predictions from the adapted equation (78 to 99% of the variability explained). Erosion associated with thawing front progression during winter warm spells led to a relative reduction in the frost front depth. Subsequently, progression of the frost front into the cliff contributed to an additional 50 cm of sediment freezing and erosion by the end of the cold season, which was not predicted by the original Stefan equation. Our findings support the hypothesis that multiple warm spells influence the amount of lateral penetration of the frost front in vertical cliffs. Copyright © 2015 John Wiley & Sons, Ltd.

Quantitative Analysis of the Dimensions and Distribution of Channelized Fluvial Sandbodies Within A Large Outcrop Dataset: Upper Cretaceous Blackhawk Formation, Wasatch Plateau, Central Utah, U.S.A

Abstract Conceptual and quantitative models of fluvial stratigraphy typically argue that alluvial architecture is driven by a combination of allogenic processes (e.g., tectonic subsidence, sea level, sediment supply), and autogenic behaviors (e.g., avulsion). We test these models via analysis of a large (c. 200 m thick by 100 km depositional-strike extent) alluvial-to-coastal-plain succession that records shoreline progradation in response to decreasing tectonic subsidence (Late Cretaceous Blackhawk Formation, Wasatch Plateau, central Utah, U.S.A.). Oblique aerial photographs and architectural panels of six nearly linear, nearly vertical cliff face “windows” were used to characterize the dimensions (apparent widths, thicknesses) and spatial distributions of channelized fluvial sandbodies. Two statistical measures, raster-based lacunarity and point-based L-function, are used to investigate whether the distribution of channelized sandbodies show significant regularity, randomness, or clustering. Over 490 channelized fluvial sandbodies are identified in the six cliff-face “windows.” From base to top of the Blackhawk Formation, sandbodies broadly increase in width and decrease in overall abundance per unit area. Clustering of sandbodies occurs relatively frequently in lower-coastal-plain strata ( 50 km from the coeval shoreline). A strong negative correlation between lacunarity and stratigraphic position is also observed, such that a wider range and greater variety of spatial gaps occurs between sandbodies in lower-coastal-plain strata relative to upper-coastal-plain and alluvial strata. Comparison with numerical modeling studies of fluvial stratigraphic architecture implies the predominance of an avulsion-generated pattern of sandbody distribution that includes an element of compensational stacking on the upper coastal plain and alluvial plain, for a range of distances from the coeval shoreline (c. 40–130 km) and tectonic subsidence rates (c. 40–700 m/ Myr). On the lower coastal plain (< 50 km from the coeval shoreline) localized clustering of channelized sandbodies is interpreted to have formed by avulsion of deltaic distributary channels downstream of delta-apex avulsion nodes, possibly modulated by low-amplitude (< 30 m) sea-level fluctuations.

Triggering upstream channel incision in the fluvial systems of the trunk valley of Wadi Watir drainage basin, South Sinai Peninsula, Egypt

Dredging the alluvial fans for repaving the international road located in the bottom of the Wadi Watir valley produced vertical cliff faces of different heights, and at different locations of the fans. The heights of the cliff faces resulted in considerable elevation differences between the surface of the dredged alluvial fans and the local base level provided by the Watir trunk valley. The principal geomorphic response to this anthropogenic intervention is triggering upstream channel incision waves at different intensities in the fluvial systems of the downstream reaches of the Watir drainage basin. The channel incision processes resulted in subsequent geomorphic adjustment scenarios that vary from widening the active channels on the surface of the dredged fans, triggering rockfalls from the adjacent hillslopes, and transporting coarse alluvial deposits from the main sediment sources of the fluvial systems, and eventually re-depositing them as sheetform gravel, channelform gravel, and new fan lobes. The major outcome of the various geomorphic adjustment processes was changing the role of the alluvial fans within the fluvial systems from buffer zones where fan aggradation was dominant into dynamic coupled zones. Being coupled zones, the dredged alluvial fans allowed high potential of mass transmission from the feeder catchment areas into the Watir trunk valley. Under such conditions, it could be stipulated that considerable changes in the morphology of landscapes are highly anticipated in response to flash flood events that intermittently occur in the Watir drainage basin.

Day-Roosts ofMyotis leibiiin the Appalachian Ridge and Valley of West Virginia

Abstract Currently there is little known about day-roosts used by Myotis leibii (Eastern Small-footed Myotis) in the Central Appalachians. To provide insights on this species' day-roosting habits, we successfully radiotracked 5 lactating females and 5 non-reproductive males to 57 day-roosts during June and July 2008. Eastern Small-footed Myotis used ground-level rock roosts in talus slopes and rock fields (n = 53), and roosts in vertical cliff faces (n = 4). Ground-level roosts had low canopy cover (males: = 14.1 ± 2.1 [SE] %, females: = 19.6 ± 3.1%), but were located close to vegetation (males: = 3.6 ± 0.4 m, females: = 4.8 ± 0.8 m). Males switched roosts every 1.1 ± 0.04 days, traveled 41.2 ± 7.8 m between consecutive roosts, and roosted 415 ± 49.0 m from capture locations. Females switched roosts every 1.1 ± 0.06 days, traveled 66.5 ± 14.6 m between consecutive roosts, and roosted 368 ± 24.0 m from capture locations. Ground-level roosts used by females were closer to ephemeral water sources ( = 226 ± 3...

Speleothems in a wave-cut notch, Cayman Brac, British West Indies: The integrated product of subaerial precipitation, dissolution, and microbes

A wave-cut notch that is deeply incised into the vertical cliff faces of Cayman Brac is adorned with stalactites, stalagmites, and columns. The prefix “notch” is applied to each type of speleothem in order to distinguish them from cave speleothems. These speleothemic deposits must have formed since the highstand, ~ 125,000 years ago, which was responsible for the development of the notch. The laminated notch speleothems are formed largely of aragonite (small and large crystals) and calcite (columnar, fiber, and grain-coating mats) along with minor amounts of dolomite, a Mg–Si precipitate (kerolite?), gypsum, and halite. Laminae, typically < 2 mm thick, are commonly bounded by dissolution discontinuities that truncate the older laminae and their formative aragonite and calcite crystals. The patchy tan, grey, to green surface coloration of the notch speleothems reflects the random distribution of the subaerial biofilms, which are formed of a diverse array of filamentous and non-filamentous microbes. The notch speleothems are the integrated product of precipitation and dissolution that was, in some places, microbially mediated. Interpretations based on their mineralogy and internal structures indicate that the composition of the formative waters must have temporally fluctuated with periods of precipitation being interrupted by periods of dissolution. The microbes that formed the subaerial biofilms may have influenced some of these processes. The aragonite, calcite, and kerolite (?) probably formed as evaporation and loss of Ca through precipitation progressively increased the Mg:Ca and the Si/(Ca + Mg) ratios. The dolomite, gypsum, and halite probably formed during early diagenesis during the evaporation of seawater that percolated into the interiors of the notch speleothems.

Effect of Cliff Shape on Internal Stresses and Rock Slope Stability

Abstract The failure of coastal rock cliffs is attributed to a variety of factors such as weathering, wave action, ground water level, and rock and joint parameters. The wave-induced undercutting of the vertical cliff face is hereby assumed to play a critical role. Very little attention has, however, been paid to the gravity-induced stresses within the cliff face. A numerical analysis of the stress distribution in idealised rock cliffs of varying slopes (50–90°) and in various stages of undercutting has been conducted. Investigated parameters included slope angle, cliff height, influence of a cliff base cavity, front face loading, and cliff surcharge loading. The analysis showed that stresses in the cliff face geometry immediately after a failure were insignificant. With the steepening of the cliff, stresses increased to reach very high values for a vertical cliff face. Additional undercutting of the cliff resulted only in a slight increase of those stress magnitudes. The steepened rock cliff can result i...

Multiconfiguration GPR measurements for geometric fracture characterization in limestone cliffs (Alps)

Rock-mass fracturing is a key parameter in rock-fall hazard assessment. However, traditional geologic observations can provide information only about discontinuities at the surface. In this case study, detailed ground-penetrating-radar (GPR) measurements (with antennas of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) were conducted on a test site, using different acquisition configurations deployed on vertical cliff faces. Conventional 2D profile data, common-midpoint (CMP) survey data, and transmission data were acquired to evaluate the potential use of radar waves to characterize the geometry and properties of the major discontinuities (fractures) within a Mesozoic limestone massif. Results showed that the continuity and geometry (orientation and dip) of the major observed fractures, which are crucial parameters for assessing rock stability, can be obtained by combining vertical and horizontal profiles measured along the cliff. We used [Formula: see text] antennae and reached a maximum penetration of [Formula: see text], which limits the technique to rock volumes of a few tens of thousands of cubic meters. We observed significant differences in reflectivity along the detected fractures, which suggests that the fractures’ characteristics vary in the rock mass. We used transmission data to obtain a radar velocity image. Although the results were consistent with radar profiles on the cliff, they showed that the technique has little utility, beyond that of more traditional GPR methods, for delineating fractures in a rock mass.

Taihangia rupestris, a Rare Herb Dwelling Cliff Faces: Responses to Irradiance

We studied the responses of gas exchange, leaf morphology, and growth to irradiance in Taihangia rupestris, a naturally rare herb inhabiting only vertical cliff faces. In low irradiance (LI, 10 % of full sun) T. rupestris had lower net photosynthetic rate (PN) and produced much less leaves, total leaf area, and biomass than in high (HI, full sun) or medium irradiance (MI, 50 % of full sun). PN of T. rupestris was higher in HI than in MI on August 8, but lower in HI than in MI on September 22. T. rupestris had shorter petioles and lower leaf area ratio, and produced more but smaller and thicker leaves in HI than in MI. In HI the fast production of new leaves may guarantee T. rupestris to maintain higher PN at the whole plant level and thus accumulate more biomass at harvest, although the single-leaf PN may become lower as found on September 22. Hence T. rupestris possesses a latent capacity to acclimate and adapt to full sun. Irradiance, therefore, may not be a responsible factor for the restricted distribution of T. rupestris on vertical cliffs.

Edge waves along periodic coastlines. Part 2

Numerical evidence of the existence of edge waves travelling along a periodic coastline consisting of a straight and vertical cliff face from which protrudes an infinite number of identical rectangular barriers, each extending throughout the water depth, is given based on a Galerkin approximation to an integral representation of the problem derived using the linear theory of water waves.

Ozobryum ogalalense (Pottiaceae), a New Moss Genus and Species from the American Great Plains

Among the bryophytes collected in northwestern Kansas by Vernon L. Wranosky of Colby, Kansas, during the summer of 1990 is a new genus and species of Pottiaceae, Ozobryum ogalalense. Subsequent collecting in the vicinity has resulted in two additional localities for this moss, one in Kansas and one in Nebraska. Ozobryum Merrill, gen. et sp. nov. TYPE: U.S.A. Kansas: Decatur County, on Ogallala Formation mortarbeds above south fork of Sappa Creek, 25 km SW of Oberlin, 39?40'N, 100?43'W, ca. 800 m, 11 Aug. 1990, Vranosky 62 (holotype, KSC; isotypes, DUKE, MICH, MO). Figures 1, 2. Planta insignis foliis obtusatis margine incrassatis quasi succulentis, cellulis utroque folii paginae grosse mamillosis, costa debili obscura utrinque cellulis mamillosis occulta bene distincta. Plants minute, growing in soft, compact cushions, to 2 cm high, dark green to yellowish green at surface of tufts, without a central strand. Leaves erect when dry, spreading at 45? or less when moist, concave, oblong-elliptic, rounded at the apex, 0.350.55 mm long, margins plane or erect. Costa ending well below the apex, thin and obscure, with 2 guide cells but no stereids, covered on both surfaces by short, bulging-mamillose cells similar to those of the lamina. Upper leaf cells bistratose (or 3-stratose) at the margins and in patches internal to the margins, rounded-hexagonal to subquadrate, ca. 7-9 Am, green and obscure, bulging on both surfaces, crowned with a broad, circular, knoblike thickening of the outer wall, centered over the lumen. Basal cells hyaline and subquadrate in a short area. Archegonial buds scattered along the stem, sometimes easily detached, with a tuft of rhizoids at the base. Perichaetial leaves smooth, ovate, acuminate, entire to unevenly serrate, the costa ending in the apex. Perigonia not seen. Paratypes. U.S.A. KANSAS: Decatur County, type locality, 30 Apr. 1991, Merrill 12888; on N-facing mortarbed cliffs, Elephant Rock, 2.5 km S of Traer, 30 Apr. 1991, Merrill 12903; Rawlins County, on mortarbeds above N fork of Sappa Creek, 22 km SE of Atwood, 11 Aug. 1990, Wranosky 69, 30 Apr. 1991, Merrill 12901. NEBRASKA: Hitchcock County, on mortarbeds exposed in arroyo, 17.6 km NW of Herndon (Kansas), 30 Apr. 1991, Merrill 12919. Voucher specimens deposited in the Reed Bryophyte Herbarium, Kans State University Herbarium (KSC). The genus name Ozobryum is derived from bryum (moss) and from the fictional Land of Oz, the creation of American author L. Frank Baum, now popularly associated with the Kansas plains. The specific epithet ogalalense refers to the Ogallala Formation, named for a locality in southwestern Nebraska. The Ogallala is the principal aquifer throughout most of the High Plains from southern South Dakota to the Texas Panhandle. The leaves of Ozobryum are highly distinctive and are characterized by their oblong-elliptic shape, the leaf cells bistratose and mamillose on both surfaces, and the reduced costa obscured on both surfaces by short mamillose cells. In its soft, dense cushions and habitat beneath ledges and in crevices on moist vertical cliff faces, Ozobryum resembles a miniature Gymnostomum. Under the hand lens the living plants have a peculiar frosted and succulent appearance due to the mamillose cells and thickened leaf margins (Fig. 2). The perichaetial leaves are strikingly different in shape from the vegetative leaves, the cells rhombic, unistratose, and smooth or only slightly roughened at the extreme apex. The female buds, which are sometimes easily detached and have a tuft of rhizoids at the base, could function as vegetative propagules, as improbable as this may seem. No brood bodies have been observed so far. At the suggestion of Richard Zander, I examined a series of 154 specimens (BUF) from Mexico and elsewhere representing his concept of Molendoa sendtneriana (B. S. G.) Limpr. (see Zander, 1977). The tropical American specimens mostly belong to the lax, glaucous-green, linear-leaved plant that corresponds to Anoectangium obtusifolium (Broth. & Par. ex Card.) Grout, illustrated by Crum & Anderson (1981). Among the Mexican specimens, however, are several that resemble Ozobryum in their small size, short blunt leaves, and thickened leaf

Form and Relation to Present Sea Level of Pleistocene Marine Erosion Features

Wind fetch and land slope are the two oceanographic factors most easily determined for ancient shores, and these factors can account for many of the variations in terrace form at different levels in one area and in different areas at the same level. On a vertical cliff face no erosion terrace is initiated, but on soluble rocks a sharp solution notch leaves a clear record of the sea level. Assuming maximum depth of erosion of rock by waves to be 30 ft., the geometry of terrace erosion is outlined, and the limiting states under conditions of varying land slope and subaerial weathering. Maximum terrace width is commonly about 3,000 ft. with a slope of about 1/100 since accumulation of a sand beach protects the cliff at this gradient. Small eustatic oscillations can cut two solution notches, two small terraces, one terrace, or one terrace and a notch, depending on the land slope and the amplitude and duration of the oscillation. Large eustatic changes tend to eliminate traces of small oscillations and to modi...

Belemnite orientation in the Hunstanton Red Rock

The long-axis direction and dip of belemnites occurring in the Hunstanton Red Rock have been measured in situ on a vertical cliff face. The belemnites are found to have an irregular lateral distribution and occur only sparingly throughout the lowest band. At first sight the evidence suggests a preferred orientation of the belemnites. The interpretation of this orientation is discussed, and it is shown to be an effect resulting from the preferred orientation of the cliff section.

Cliff Profiles of Devon and Cornwall

The coast scenery of North Devon and of North and West Cornwall con? sists mainly of rugged cliffs, ranging in profile from the hog's-back slopes around Lynmouth to the sheer precipices of Morwenstow. The loftiest hog'sback cliffs (Plate i) are those in north-east Devon between Combe Martin and Foreland Point, extending still farther east across the Somerset border. The Great Hangman near Combe Martin has a crest 1044 feet above sealevel about 300 yards inland, whence a straight vegetated slope of gradient approaching 1 in 1 descends to the very base, which alone is now subject to wave attack. The clifTs between Hartland Point and Widemouth afford a complete contrast. An inland plateau sloping gently towards the sea is cut clean by an almost vertical cliff face, 400 feet high near Morwenstow and nearly 300 feet high at Hartland Quay (Plate 2). Where the profile, as at the Lizard and the Land's End, does not conform to either of these two extremes, a vegetated slope curves in a bevel from the level surface above to the vertical cliff face below. The curve may be concave (Plate 3) or convex (Plate 4). The greater part of the area considered in this paper (see map) consists of Devonian and Carboniferous rocks. Along the coast the commonest of these are hard grits, shales, sandstones and slates; there are also small outcrops of Devonian igneous rocks. At the end of the Carboniferous period the region was evidently subjected to severe pressure along Armorican lines, resulting in a series of folds with east and west strike. The north of the area is occupied by a great synclinorium, so that in North Devon the regional dip is to the south while along the coast, roughly from Boscastle to Morwenstow, it is to the north. During the same orogeny the great granite domes of Devon and Cornwall were intruded, which outcrop on the mainland coast at the Land's End.