Surficial Deposits Research Articles

Estimation of rippability and excavation conditions in calcrete deposits with seismic refraction methods

Seismic P-wave velocities in surficial materials, determined from seismic refraction surveys, can be used to assess excavation conditions at engineering sites such as roads and pipelines. These velocities are important in establishing whether and to what extent blasting is required. Certain contractors have produced rippability versus seismic velocity charts which are widely used to assess excavation conditions on a preliminary basis. Unfortunately these charts are limited in the number of rock types included and fail to take account of other complicating factors such as degree of weathering and nature of occurrence. They are particularly limited in treating surficial deposits such as calcrete, the nearest charted equivalent being caliche which may or may not be equivalent to calcrete.

La végétation forestière du cap Saint-Jacques, île de Montréal, Québec

As part of a study of the forest vegetation of the Island of Montreal, 10 stands of deciduous hardwoods of Cap Saint-Jacques were sampled with the quarter method. Indirect ordinations indicate that the floristic organization of these urban forests is mainly due to surficial deposits and moisture regime in addition to the types and the intensity of disturbances.

Distribution and Aspects of the Ecology of the Genus Tabellaria Ehr. (Bacillariophyceae) in the Northcentral United States

The ecology and distribution of four taxa of the diatom genus Tabellar?a (Bacillariophyceae), recognized by Koppen in the N- central United States, were investigated. All four were abundant in the portion of the study area mantled with noncalcareous to weakly cal- careous surficial deposits. In addition, the distribution of the genus correlated with the dominant presettlement vegetation pattern in the study area. Tabellar?a fenestrata and T. floeculosa strain IV were, for the most part, restricted to waters located in noncalcareous to weakly calcareous surficial deposits. These waters tend to be very soft to soft and oligo- dystrophic. The distribution of T. flocculosa var. linearis extends from the noncalcareous to calcareous drift areas, occurring in some lakes which are classified as moderately hard-water to hard-water and meso- trophic to eutrophic. Tabellar?a flocculosa strain III was encountered in all types of waters described above and in addition was found in many more lakes located in areas with calcareous deposits and considered as very hard-water and eutrophic.

A study of strontium isotopes in lakes and surficial deposits of the ice-free valleys, southern Victoria Land, Antarctica

The ice-free valleys of southern Victoria Land, Antarctica, contain saline lakes including Lake Vanda in Wright Valley and Lake Bonney in Taylor Valley. The source of the salts dissolved in the brines has not yet been identified. Strontium in water-soluble salts of soil samples in Wright Valley has 87 Sr 86 Sr ratios ranging from 0.7119 to 0.7157 with an average of 0.7144 ± 0.0008 (1 σ). This value is very similar to the 87 Sr 86 Sr ratio of brines in Lake Vanda ( 87 Sr 86 Sr = 0.7149 ± 0.00017 ), but differs significantly from the 87 Sr 86 Sr ratios of seawater (0.7094 ± 0.00012) and basaltic rocks of the McMurdo Volcanics (0.7044 ± 0.00046). The Sr in Lake Vanda therefore could not have originated from seawater or from volcanic rocks of the area, but may have been derived by chemical weathering of the igneous and metamorphic rocks exposed in Wright Valley. The 87 Sr 86 Sr ratios of Lake Bonney are invariant with depth and average 0.7130 ± 0.00014 (1 σ), whereas the Sr concentrations increase from 0.7345 ppm near the surface to a maximum of 39.92 ppm at a depth of 25 m. The Sr concentrations at greater depth decrease slightly to 35.88 ppm at 30 m. The Sr in water-soluble soil salts near Lake Bonney and of the Taylor Red Cone is similar isotopically to the Sr in the lake. The 87 Sr 86 Sr ratios of soil salts and of meltwater in Taylor Valley decrease systematically from Lake Bonney toward the coast. The water in Lake Fryxell, which is closest to the coast, has an 87 Sr 86 Sr ratio of 0.7090 and is identical to that of seawater. The evidence from this and similar studies in other parts of the world indicates that the 87 Sr 86 Sr ratios of saline brines in closed continental basins are representative of the Sr in the rocks underlying the basin. The Sr in carbonate and sulfate minerals precipitated from such brines preserves the 87 Sr 86 Sr ratios that existed at the time of deposition. Because of these relationships we suggest that stratigraphic variations of the 87 Sr 86 Sr ratios of non-marine carbonate or sulfate rocks reflect changes in the geology of the drainage basin. The isotopic composition of Sr of such rocks may therefore provide useful information about the geologic histories of continental basins.

Morphology and distribution of residual limestone hills (mogotes) in the karst of northern Puerto Rico

Research Article| March 01, 1978 Morphology and distribution of residual limestone hills (mogotes) in the karst of northern Puerto Rico M. J. DAY M. J. DAY 1Department of Geography, University College Dublin, Belfield, Dublin 4, Ireland2Present address: Department of Geography, University of Wisconsin — Milwaukee, Milwaukee, Wisconsin 53201 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1978) 89 (3): 426–432. https://doi.org/10.1130/0016-7606(1978)89<426:MADORL>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation M. J. DAY; Morphology and distribution of residual limestone hills (mogotes) in the karst of northern Puerto Rico. GSA Bulletin 1978;; 89 (3): 426–432. doi: https://doi.org/10.1130/0016-7606(1978)89<426:MADORL>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Limestone towers, residual hills occurring in northern Puerto Rico, between Arecibo and Manati, have been examined by field investigation and photogrammetry. Previously, these landforms have been described only qualitatively; in this paper summit densities, heights, diameters, planimetric shapes, and orientations are quantified.Tower heights are generally less than 25 m; diameters range from 10 to 200 m. Diameter/height ratios range from 1.42 to 7.50. These values place the hills in the Sewu class of Balazs' (1971) classification of tropical karst styles. Towers are predominantly elongate in plan view, and pronounced long-axis orientations are evident. Tower summits exhibit a distribution that approaches uniformity.The relationship between the residual hills and the adjacent cockpit karst area indicates a similar origin for both areas, with differences in summit densities relating to the distribution of surficial deposits, which promote subsurface corrasion. Tower slope asymmetry occurs only in 35% of cases, and it is probably related to basal erosion, induration of the limestone surface being of secondary importance. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

A System of Engineering Geology Mapping Symbols

Research Article| January 01, 1977 A System of Engineering Geology Mapping Symbols RICHARD W. GALSTER RICHARD W. GALSTER Richard W. Galster is Chief, Geology Section, U. S. Army Engineer District, Seattle, Washington. Search for other works by this author on: GSW Google Scholar Environmental & Engineering Geoscience (1977) xiv (1): 39–47. https://doi.org/10.2113/gseegeosci.xiv.1.39 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation RICHARD W. GALSTER; A System of Engineering Geology Mapping Symbols. Environmental & Engineering Geoscience 1977;; xiv (1): 39–47. doi: https://doi.org/10.2113/gseegeosci.xiv.1.39 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract A simplified and universally applicable system is proposed, to be used for designating surficial deposits and types of bedrock on maps intended for use in engineering and environmental geology. The system combines a single capital letter designating origin of the deposit and one or more lower case letters symbolizing the lithology. Under special conditions qualifying symbols are added parenthetically where they apply. Mappable units having the same symbol are differentiated by a hyphen followed by an Arabic number. Bedrock types are symbolized simply by two capital letters. The system can be quickly memorized and appears readily adaptable for nearly all geologic areas and conditions. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Geomorphological significance of late quaternary deposits of the Lake George Area, N.S.W.

Summary A dated stratigraphy of surficial deposits is described for the Lake George area in the Southern Highlands of New South Wales. It includes lacustrine‐littoral, alluvial and aeolian sediments. The oldest stratigraphic reference is the highest strandline of the much enlarged late Pleistocene Lake George, at 30–37 m above the present lake bottom and with a dated age range of 21 000–27 000 y B.P. Five subsequent periods of shoreline aggradation have already been established. Four stratigraphic units were identified in aeolian deposits on the eastern side of Lake George. They indicated periodic instability to wind of lake margin deposits during the interval 23 000 to 2000 y B.P. Dated stratigraphies of alluvial fans and valley fill deposits in the Lake George Basin, and in the adjacent Grove Creek Basin, also reflected periodic instability of hillslope terrain during the last 30 000 years. Evidence available in the area suggested that accelerated fan building and valley aggradation were contemporaneous...

Methods of terrain evaluation, Mackenzie Transportation Corridor, N.W.T., Canada

In 1971 and 1972, the Terrain Sciences Division of the Geological Survey of Canada carried out the largest mapping program in its history of the distribution and characteristics of terrain types. Over 140.000 mile2 (360,000 km2) of the Mackenzie Transportation Corridor was evaluated. This information was supplied to the public, industry and government in order to plan and design projects properly, by efficiently utilizing natural resources and minimizing environmental damage. The requirements of potential users varied to such a degree that it was decided to map the ‘basic’ geology and other terrain characteristics so that derivative maps could be constructed for specific uses. A mapping system was devised for surficial deposits using genesis as the primary unit, modified by texture and morphology. Organic and permafrost terrain were included, factors not ordinarily a part of traditional geological mapping. The system was comprehensive and flexible enough to include such aspects as the percentages of minor units, unit thickness, and slope and other morphological characteristics. In bedrock and unglaciated areas, a second system based upon the same principles as the first but arranged in a different manner was devised. In this case, the primary unit is based upon relief, with additional information on lithology of the bedrock, texture of overlying debris, and broad morphological and slope characteristics. Comprehensive legends were prepared. Using the mapping units as the base, the legends were divided into various categories, providing information on the composition, ground ice content, thickness, and engineering characteristics of the deposits, and surface characteristics including topography, drainage pattern, vegetation, and dominant soils (pedologic sense).

Correlation of tectonically deformed shorelines on the southern Atlantic coastal plain

The assumption of absolute tectonic stability during Pleistocene time has influenced most previous attempts to map, name, and correlate relict shorelines and surficial deposits on the southern Atlantic coastal plain. This study is the first to correlate shorelines throughout the region independently of that assumption. Topographic shoreline features were mapped and differentiated into age groups on the bases of progradational discontinuities, contrasts in the state of preservation, and changes in coastal morphology. Three shoreline sequences are well preserved, permitting paleogeographic reconstructions. A combination of published and direct geomorphic evidence suggests that all three shoreline sequences have been deformed. Warping continued through Pleistocene time, following persistent Cenozoic structural features.

Soil‐landscape Relationships in the Occidental Plateau of São Paulo State, Brazil: II. Soil Morphology, Genesis, and Classification

AbstractNine profiles representing the major soils in the Occidental Plateau of São Paulo State, Brazil, were characterized after detailed geomorphic and soil mapping were completed on a 70.8 km2 area. The stable upland geomorphic surface had Oxisols, surrounded by younger erosional surfaces with Ultisols, Alfisols, and Inceptisols. Mollisols formed where the erosional surfaces exposed calcareous sandstone. The argillic horizons of the Ultisols and Alfisols in these positions apparently have formed in material that would qualify as an oxic horizon before it was exposed. Laterally moving water at these sloping sites is believed to initiate free Fe removal and lessivage. Lateral water movement at the contact between the surficial deposits of oxic composition and the underlying calcareous sandstones appears to supply the bases for the Alfisols developed in the oxic material.Kaolinite dominates the clay mineralogy of the soils formed in unconsolidated deposits, but attapulgite and smectite are present in the calcareous sandstone. In the soils shallow to calcareous sandstone the attapulgite apparently has weathered to smectite within a few centimeters of the rock.

Soil‐landscape Relationships in the Occidental Plateau of São Paulo State, Brazil: I. Geomorphic Surfaces and Soil Mapping Units

AbstractThis study was conducted in a 70.8 km2 area that includes most of the soils and landscapes present in the Occidental Plateau region of São Paulo State, Brazil. Surficial deposits of unknown derivation and age and Cretaceous age carbonate cemented sandstone are the soil parent materials. Both geomorphic surfaces and soils were mapped. Surface and subsurface soil chemical and physical characteristics of 103 sites were summarized to evaluate the soil variation of geomorphic surfaces and soil mapping units.Soil properties that are expressions of weathering indices are related to geomorphic surface, but clay illuviation, base saturation, and carbon content do not regularly increase or decrease from the oldest to the youngest surface.More than one soil mapping unit can be found on one geomorphic surface. Most soil physical and chemical properties have smaller coefficients of variation when grouped by soil mapping unit than when grouped by geomorphic surface.

Correlation of aeroradioactivity and geology in southeastern Connecticut and adjacent New York and Rhode Island

Radioactivity patterns in southeastern Connecticut, adjacent Rhode Island, and New York closely reflect bedrock units. This relationship is not greatly affected by surficial deposits of Pleistocene age because most deposits are locally derived and bedrock outcrops are relatively abundant. Most bedrock units are medium- to high-grade metasedimentary, metavolcanic, and metaplutonic rocks that range in age from possible Precambrian to middle Paleozoic. The rest are postmetamorphic granite and pegmatite of late Paleozoic age. The area is on the west flank of an anticlinorium of granitic gneiss and subordinate metasedimentary and metavolcanic rocks at a place where the anticlinorium changes trend from north to east. The Honey Hill and Lake Char faults mark a zone of low-angle faulting between the granite-gneiss terrane and stratified rocks of the Merrimack synclinorium to the north and west. The east-trending Honey Hill fault marks the southern end of the Merrimack synclinorium. Four fields denoting different levels and patterns of radioactivity coincide with major geologic provinces. The granite-gneiss terrane, which contains abundant potassic, ledge-forming granitic rocks (the Sterling Plutonic Group), coincides with a field of relatively high radioactivity, in which subordinate lows reflect outcrop areas of quartzitic rocks of the Plainfield Formation. This terrane is flanked to the west and north by layered metavolcanic rocks of mafic to intermediate composition belonging mostly to the Quinebaug Formation. These rocks coincide with a field of relatively low to moderate levels of radioactivity. The lowest level within this field is produced by the Preston Gabbro, which is at the right-angle bend in the structure. A sequence of metasedimentary schist and gneiss of the Tatnic Hill Formation, Hebron Formation, Scotland Schist, and the sill-like Canterbury Gneiss overlies the Quinebaug Formation. These rocks produce a field of moderate levels of radioactivity but have nodes of high radioactivity where pegmatite is abundant. A field of moderate intensity south of the east-trending anticlinorium of granitic gneiss coincides with layered and massive granodioritic and quartz-dioritic gneiss and subordinate amphibolite equivalent stratigraphically to the layered metavolcanic rocks north of the anticlinorium. The late metamorphic to postmetamorphic, low-angle Honey Hill and Lake Char faults, which follow the bend in the structure at the base of and within the metavolcanic rocks on the north and west sides of the anticlinorium, respectively, can be recognized only by the radiometric pattern that reflects the tectonic pinch-out of the Quinebaug Formation westward along the Honey Hill fault. A pluton of Narragansett Pier Granite of late Paleozoic age, which has associated dikes of Westerly Granite, is reflected in a sub field of high radioactivity in southern Rhode Island. Material derived from these rocks is apparently responsible for a relatively high level of radioactivity in the Charlestown moraine immediately south of the out crop area.

Cartographie géotechnique ville de Bécancour

The geotechnical map of a region comprises several documents including the map of surficial deposits, depth of overburden, natural slopes and hazards, bedrock contours and geology, synthesis and land use. The land use map reproduces the other documents and shows the areas appropriate for development as a function of the soil bearing capacity, ground and slope stability, ease of excavation, etc.The maps are prepared from available information such as reports, maps, and field data obtained from borings, penetration and vane tests, and geophysical surveys. [Journal translation]

Moss-Lichen Flora of St. Elias-Kluane Ranges, Southwestern Yukon

One hundred eighty-nine moss taxa including 181 species and 193 lichen taxa including 190 species are reported from the St. Elias-Kluane Ranges, southwestern Yukon (60'-62' N, 137'-141' W). Sixteen of the moss taxa and 74 of the lichen taxa represent new records for the Yukon. The list includes all literature reports as well as recent collections. In many regions of North America our knowledge of the moss and lichen floras is sparse in comparison with the vascular plant flora. This is especially true for the more northern areas. This paper provides a checklist of mosses and lichens for one of these areas; the St. Elias Mountain-Kluane Ranges in the southwestern Yukon (60'620N, 1370-141oW). GEOLOGY AND GEOMORPHOLOGY The geologic history of the St. Elias-Kluane Ranges has been presented in detail by Sharp (1943), Bostock (1952), Kindle (1952) and Muller (1967). In general, the mountains consist of a complex eugeosynclinal assemblage of sedimentary, volcanic and intrusive rocks with established ages ranging from Devonian to early Tertiary (Muller, 1967). Common rocks in the northern sector of the region include greenstone, greywacke, quartzite, slate, phyllite, marble, argillite, granite and granodiorite. Farther south, shale, sandstone, andesite, basalt and other volcanic rocks become important. During the Pleistocene most of the St. Elias-Kluane Ranges were covered by ice at various times with the ice sheet ending just north of Kluane Lake. Ice filled all the valleys in the Kluane Ranges to elevations of 1825-1980 m (Kindle, 1952; Day, 1962; Muller, 1967). This extensive glaciation resulted in widespread deposits of glacial till. Lacustrine parent materials are also important in the region, most notably in the Alsek and Dezadeash River valleys where a large proglacial lake (Recent Lake Alsek) was dammed by the Lowell Glacier about 125 years ago and had an upper shoreline at either 1The following taxonomists kindly identified some of the more difficult specimens: H. Ando, I. M. Brodo, Z. Iwatsuki, T. Koponen, E. Lawton, K. E. Ohlsson, M. Ostafichuk, W. L. Peterson, H. Robinson, A. C. Skorepa, J. W. Thomson, W. A. Weber and P. Y. Wong. We also thank Gloria G. Douglas for her aid in the field and in preparation of the manuscript. We are grateful to the National Research Council of Canada (Grant No. A6390) and to the National and Historic Parks Branch of the Department of Indian and Northern Affairs through the Canadian Wildlife Service, Department of Environment, for funding this research. Laboratory facilities provided at Kluane National Park Headquarters are also appreciated. 2 Department of Botany, University of Alberta, Edmonton, Alberta, Canada T6G 2E9. 3 Present address: Douglas Ecological Consultants Ltd., 202-737 Fort Street, Victoria, British Columbia, Canada V8W 2V1. This content downloaded from 207.46.13.128 on Tue, 06 Sep 2016 05:46:37 UTC All use subject to http://about.jstor.org/terms 438 THE BRYOLOGIST [Volume 79 640 m (Kindle, 1952) or 604 m (Johnson & Raup, 1964). Other surficial deposits in the region include alluvial gravels, sand dunes and loess. The latter is most abundant in the Slims River valley where constant winds create dust clouds that blow eastward to Kluane Lake.

Stratigraphy and origin of surficial deposits in sinkholes in south-central Indiana

Sinkholes in the karst area of south-central Indiana contain, from oldest to youngest, (1) sandy calcareous mud; (2) red clay and red silt, both facies commonly known as terra rossa ; (3) chert gravel; (4) loess; and (5) yellowish-brown silt derived from loess. The nature and distribution of litho-stratigraphic units suggest the filling of bedrock basins. The terra rossa in the sinkholes is primarily a transported sedimentary deposit. The source of much of the terra rossa sediment is probably the adjacent uplands.

Exploration for zinc and lead in western Newfoundland based on geochemical surveys

Exploration for zinc and lead in the Paleozoic carbonates of western Newfoundland has relied heavily on geochemical techniques. In the Goose Arm—Raft Pond area north of Corner Brook, stream silt and lake sediment geochemistry defined coincident anomalous areas which were then covered by reconnaissance soil sampling grids. This reconnaissance survey confirmed and detailed some anomalies around Raft Pond while allowing other areas to be rejected. A study of the surficial deposits in the Raft Pond area revealed that the anomalous soils were derived from either slopewash or from local glacial fans, information useful in later prospecting. In 1974, exploration was concentrated on the Raft Pond area and on the Goose Arm Peninsula where Zn-Pb showings had been located earlier. Detailed soil grids were sampled in the two areas and cumulative frequency curves were plotted on probability paper for the Fe, Zn, and Pb analyses to identify background and anomalous populations. When geological mapping was completed, soils overlying limestone were separated from those overlying dolostone and the calculations were repeated. In most cases, this allowed a clearer interpretation of the data and a more accurate definition of anomalies. In addition, the analysis indicated that lead mineralization probably did not occur in particular lithologies in the area. Low-grade zinc occurrences in dolostone of the St. George Group were found associated with many geochemically anomalous areas. There did not appear to be a relationship between the intensity of the anomaly and the grade of mineralization in bedrock. Also the amount of accuracy provided by the detailed soil survey was superfluous once the type of sphalerite occurrence was recognized. In this terrain, a soil grid with sample centres 500 ft (150 m) apart might be the optimum aid to exploration.

Effects of Agriculture on Erosion and Sedimentation in the Piedmont Province, Maryland

A study of surficial deposits in the Piedmont province of Maryland has made it possible to construct a balance equation of sediment production and deposition since erosive agricultural land use began in the 1700s. Truncated Piedmont upland soil profiles imply approximately 0.15 m of soil erosion. In Western Run, a basin 155 km2, consisting of 85 percent Chester and Manor soils, this amounts to 130 × 10−3 hm3/km2 of eroded sediment. Reservoir sedimentation rates imply that 34 percent of the eroded sediment has been carried out of the system. The rest of the sediment remains in the watershed as alluvium in the upper 1 m of flood plains and as colluvium and sheetwash deposits on hillslopes. Agricultural sediment stored in flood plains constitutes 14 percent of the estimated soil erosion. The sediment was deposited mostly by overbank deposition at rates as high as 1.6 cm/yr. The remaining 52 percent of the eroded sediment occurs as colluvium and sheetwash deposits on hillslopes and as fan-shaped colluvial-alluvial deposits at junctures of headwater tributaries. Wood from such deposits was radiocarbon dated at 290 ± 100 yr. A buried junk pile in a flood plain yielded license plates whose dates imply that after 1925 the dump was buried by overbank deposition at rates as high as those for a basin undergoing urbanization. Piedmont basins less than 26 km2 have statistically longer bankfull recurrence intervals than streams with drainage areas greater than 26 km2. This suggests that since the decline of agricultural land use in the early 1900s, small upland tributaries have adjusted to decreased sediment loads by entrenchment into and erosion of sediment deposited since the initiation of colonial agricultural land use.

SEM Study of Marine Ferromanganese Micronodules from the Atlantic Ocean

Recently there has been increased research on deep ocean ferromanganese n odule deposits due to interest in mining them for their Ni, Co and Cu content (up to 1%). In addition to the scattered surficial deposits of nodules (dia &gt; 10 mm) there are also micronodules (dia &lt; 1 mm) which are much more widespread and seldom studied. Several cores sampled for the present study were taken in the abyssal plain and hills region (depth &gt; 5000 m) of the Northwest Atlantic Ocean (obtained 1973 by S.K.A. aboard R/V Conrad cruise R-16). The micronodules were separated by sieving the coarse fraction &gt; 62 μm), which composed up to 10% by dry weight of the surface sediment, decreasing to 1% at depth (9m) and consisting mainly of ferromanganese micronodules with small amounts of quartz and biogenic material. An initial survey has been completed utilizing reflected light microscopy and scanning electron microscopy (JEOL JSM-U3 equipped with an EDAX energy dispersive X-ray spectrometer) in preparation for a more extensive study of the microstructure, mineralogy and chemistry of the micronodules and sediment.

Deglaciation of Port Hood Island, Nova Scotia

A palynological study and radiocarbon dating of surficial deposits on Port Hood Island, Nova Scotia, have indicated that deglaciation occurred more than 11 000 yr B.P., and that the presence of an 'upper till' in local depressions is attributable to soil-creep processes under cold and wet climatic conditions some 11 000 to 10 000 yr B.P. No evidence was found of an ice advance younger than 11 000 yr B.P. in western Cape Breton Island.

Chemical weathering of tills and surficial deposits in East Baffin Island, NWT, Canada : Andrews, JT Miller, GH 22. Intern. Geogr. Congress, 1972, Ed. W.P. Adams. 7R. Proceedings, 22 Internat. Geogr. Congress, Montreal, 1972, V.1, P5–7

Chemical weathering of tills and surficial deposits in East Baffin Island, NWT, Canada : Andrews, JT Miller, GH 22. Intern. Geogr. Congress, 1972, Ed. W.P. Adams. 7R. Proceedings, 22 Internat. Geogr. Congress, Montreal, 1972, V.1, P5–7