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Chesapeake Bay
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Water Resources and Hydrological Systems, 2020
Evidence indicates that the modern Chesapeake Bay began forming approximately 35 million years ago with a meteorite impact in the proximity of what is now the confluence of the Bay with the Atlantic Ocean.[2,3] The impact created a topographic depression that influenced the location and alignments of several large river valleys, including those associated with the present day Susquehanna, Rappahannock, and James Rivers. Since then, the river valleys have been periodically exposed and flooded in response to cycles of global glaciation and associated fluctuations in sea level. The most recent, the Wisconsin glaciation, began retreating approximately 18,000 years ago. The retreat resulted in a rise in sea level by almost ninety meters, drowning the river valleys and forming the current Bay.
Subsidence and related features in the Tully Valley, Central New York
Published in Barry F. Beck, Felicity M. Pearson, Karst Geohazards, 2018
The Tully Valley is the southern end of the north-south trending Onondaga Trough which extends from Syracuse to Tully. It is located within the Appalachian Upland, approximately 12 miles south of the Appalachian Plateau’s northernmost border along the Onondaga Escarpment. The valley owes most of its present-day appearance to late Wisconsin glaciation which is primarily responsible for the characteristic U-shaped bedrock surface and presence of most of the unconsolidated deposits (von Engeln, 1961). The southern end of the valley is blocked by morainal deposits which are part of an extensive east-west trending system known as the Valley Heads Moraine. The northern end of the valley is located at the confluence with Cedarvale Valley, an east-west trending glacial meltwater channel (Krall, 1960).
Paleolimnological assessment of long-term changes in a boreal recreational lake of the Fermont mining region (subarctic Quebec, Canada)
Published in Lake and Reservoir Management, 2020
Olivier Jacques, Reinhard Pienitz, Ghassen Ibrahim
The Fermont region is part of the parautochthonous belt in the Grenville geological province of the Canadian Shield (Rivers et al. 1989). It is also located in the southern part of the Labrador Trough, rich in iron ore deposits (Neal 2000). The bedrock is mainly composed of gneisses, schists, and metasedimentary iron units, including small amounts of carbonates that are overlain by younger layers of gabbros, granites, syenites, migmatites, and amphibolites. These are covered by Pleistocene-age and recent deposits of clay, sand, gravel, and erratic boulders of the last Wisconsinan glaciation (Clarke 1960, Murphy 1960). Deglaciation of the Laurentide Ice Sheet occurred around 6.8–7.5 ka BP (Occhietti et al. 2011). Regional topography is characterized by a rugged (hilly) high plateau terrain situated at elevations between 570 and 700 m a.s.l.