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Sediments and Sedimentary Rocks
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Depressions in ice, caused by streams flowing on the tops, or at the sides of glaciers, commonly collect sediments. Subsequently, when the glacial ice melts, irregularly shaped, often steep-sided hills of glacial debris can be left behind. These hills or mounds, called kames, consist of sand, gravel, and till. Kames are highly variable but are, typically, meters to tens of meters in longest dimension. Water flowing on the ground beneath glacial ice, too, can create river channels that collect sediment. After the glacial ice melts, the channel sediment may be left behind as an esker, a ridge that resembles an upside-down stream. Eskers contain stratified drift, mostly gravel and coarse sands, deposited by water that once flowed through tunnels beneath glacial ice.
Glacial geology
Published in Barry G. Clarke, Engineering of Glacial Deposits, 2017
Meltwater emerging from a glacier carries debris to form outwash fans, kames and kame terraces. The debris spreads out in front of the ice margin and backs over the ice; therefore, the topology of the glaciofluvial landforms depends on their location with respect to the ice margin, the presence of buried ice and the amount of transported sediment. Braided river systems develop downstream of the ice margin creating an outwash fan as the glacial debris is deposited (Figure 2.29). While these river systems form at the ice margins, they can contain buried ice, which on melting leads to kettle holes, water-filled pits that are gradually filled with further glacial debris possibly leading to conical lenses of distinctly different materials from the surrounding outwash fan. If the outwash fan crosses an extensive area of ice as the ice melts, it creates a hummocky surface to the rear of the outwash fan known as kame and kettle (hollows) topography. Kames, consisting of well-sorted deposits of sand and gravel, are formed at the ice margin creating either isolated hummocks or broad flat-elevated areas (Figure 2.30). The velocity of meltwater reduces rapidly as it emerges from a glacier resulting in coarser materials being deposited near to the outlet and finer material being carried further afield (cf. pipe discharge into a lagoon). As the ice retreats, the meltwater may be diverted along the ice margin creating a kame terrace. Kames can vary from a few hundred metres to over a kilometre in length. Kame terraces form parallel to the direction of ice flow from streams running along the sides of a glacier.
Evaluating the impact of different types of stabilised bases on the overall performance of flexible pavements
Published in International Journal of Pavement Engineering, 2019
Andraé Francois, Ayman Ali, Yusuf Mehta
Five field sections located on Route 165 (between utility poles 304 and 521) in Rhode Island (RI) were evaluated in this study. These sections are part of a controlled study currently being conducted by RI Department of Transportation (RIDOT) to evaluate their long-term field performance. A summary of the five field sections is presented in Table 1. Four of the five sections were constructed using stabilised base layers and one was constructed as a control section using untreated reclaimed asphalt pavement (RAP) aggregates base. Four different stabilising agents (i.e. calcium chloride, emulsified asphalt, Portland cement and geogrids) were utilised to construct the four stabilised base layers. All these sections were constructed in 2013. All the test sections were constructed on glacial till and stratified kame that contained deposits of sand, gravel, silt, peat and organic silt. The natural soil beneath the test sections had a plasticity index of zero, a low shrink–swell capacity, and an AASHTO soil classification that ranged from A-1 to A-4. It is important to note that the natural soil had a high water table due to the presence of granite near its surface and a high susceptibility to frost action.
Regional curves to support stream restoration initiatives in Southern Ontario
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2019
Trevor Chandler, Heather Amirault
Three regions were selected in southern Ontario for detailed study: Waterloo, Peel and York-Durham (Figure 1). These regions are located near large urban centers where future stream restoration is considered likely. Watercourses were selected in each region by reviewing topographic, physiographic and geological mapping, as well as aerial imagery. All potential creek sites were located where the topography was generally flat to gently undulating. Quaternary geology maps (Chapman and Putman 1984; Karrow and Easton 2005) were used to restrict sites to areas with similar surficial geology, which consisted of glacial till plains in the southern Peel region (Karrow and Easton 2005) and in the southern York-Durham regions (Sharpe 1980). In the Waterloo region, kame moraine (sand and gravel) dominated local geology (Karrow 1987, 1993a, 1993b).
Early Cretaceous glacial environment and paleosurface evolution within the Mount Painter Inlier, northern Flinders Ranges, South Australia
Published in Australian Journal of Earth Sciences, 2020
S. B. Hore, S. M. Hill, N. F. Alley
The East Painter exposures can be described as unsorted breccia and may be interpreted to represent a mixture of periglacial flow deposits and landslide and avalanche deposits that have incorporated various facies from hill slopes such as till and kame-terrace materials. The mass flows follow the slopes but exhibit crude bedding. The diamictite is well exposed at the East Painter No. 4 adit and on the basis of its lithology could be interpreted as a tillite (Figure 13g–i). At the northern side of the portal, the tillite unconformably rests upon an irregular surface cut across granite.