China
Africa
Explore chapters and articles related to this topic
Case Study: Adirondack Park, NY
Published in Timothy J. Sullivan, Aquatic Effects of Acidic Deposition, 2019
Because SO42- concentrations in most Adirondack lakes are so much higher (typically by approximately 100 μ64/L) than NO3- concentrations during the fall season, it has generally been assumed that SO42- is the dominant cause of mineral acidity in these lakes. This is not necessarily the case, however, particularly if NO3- and SO42- follow different hydrological pathways in reaching the lakes. A significant proportion of the observed lake-water NO3- in the fall sampling of ELS-I can be attributed to direct precipitation inputs of NO3- to the lake surfaces (Sullivan et al., 1997). This is consistent with the expected high retention of N in forest soils, and provides a mechanism to explain what may be the greater acidifying potential of in-lake NO3- as compared to in-lake SO42- in these lakes. If most or all in-lake NO3- was derived from direct precipitation inputs, this NO3- would be expected to decrease lake-water ANC stoichiometrically. If most in-lake SO42- was derived, in contrast, from deposition to watershed soils, this in-lake SO42- would be expected to decrease lake-water ANC by a substantially smaller amount because base cations mobilized from watershed soils would have neutralized much of the SO42- acidity before the SO42- reached the lakes.
Metamorphic 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
Many nonfoliated metamorphic rocks are dominated by a single kind of mineral. In these rocks, individual mineral grains or crystals, which may start small, recrystallize (grow together) during metamorphism to produce larger crystals. Figure 10.15, for example, shows an 8 cm wide rock consisting almost entirely of coarse blue calcite. This rock, which comes from the Valentine Mine in the western Adirondack Mountains, New York, derived from a limestone protolith. Petrologists use the term marble for all metamorphic carbonate rocks—rocks that form from limestone or dolostone—dominated by calcite or dolomite. (This sometimes leads to confusion because builders and others use the same word to describe any polished slab of rock.)
LiDAR-based mapping of paleo-ice streams in the eastern Great Lakes sector of the Laurentide Ice Sheet and a model for the evolution of drumlins and MSGLs
Published in GFF, 2018
Shane Sookhan, Nick Eyles, Niko Putkinen
The eastern part of the area of study includes the high standing Catskill Mountains, which is the uplifted easternmost margin of the Allegheny Plateau, and the Adirondack Mountains which is a large outlier of Canadian Shield crystalline rock (see Carr et al. 2000; McLelland et al. 2010). The south-flowing Hudson Valley was a major conduit for Quebec-sourced ice moving south to the Atlantic seaboard and which constructed the large terminal moraines of Long Island. The Catskill Mountains form the southern margin of the Mohawk Valley which drains eastwards to the Hudson Valley; this valley together with the westwards draining Oneida Lake basin forms an almost continuous west-east depression that links the Erie-Ontario lowlands with the Hudson Valley. This depression is flanked to the north by the Tug Hill Plateau which is a large high-standing outlier of Cambro-Devonian strata (Wallach & Rheault 2010). As will be related below, the presence of high topographic areas and confined lowlands principally underlain by soft Paleozoic shales, was a key factor in controlling the location of paleo-ice streams during the closing stages of the last glaciation.