Nappe

a large-scale geological structure (tens of kilometres) occurring as a sheet of rock which has been pushed over a fault plane or THRUST at the base. They are formed due to compression, but an alternative mechanism is the sliding due to gravity along a low angle fault, as seen in the Swiss Alps. In many cases, the origin of nappes may be due to a combination of both mechanisms.

Taken from Dictionary of Science

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In geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1.2 miles) or 5 km from its original position. Nappes form during continental plate collisions, when folds are sheared so much that they fold back over on themselves and break apart. The resulting structure is a large-scale recumbent fold. The term stems from the French word for tablecloth.

Nappes or nappe belts are a major feature of the European Alps, Carpathians and Balkans. The concept was developed by the French geologists who unraveled the complex tectonic history of the Alps, led by M.A. Bertrand, who identified the feature as nappe de charriage. In Switzerland it was A. Escher von der Linth and M. Lugeon. At the same time, nappe structure was investigated in northwestern Scotland by Ch. Lapworth. The Austroalpine nappes of the eastern Alps consist of a series of three thrust-faulted nappe stacks which overlie the three older Penninic nappes in this very complex system.

Taken from Wikipedia

Water Table

the level below which water saturates the available spaces in the ground. A spring or river is formed when, due to geological conditions, the water table rises above ground level. The position of the water table varies with the amount of rainfall, loss through evaporation and percolation through the soil.

Taken from Dictionary of Science

Ice Age

the spreading of ice as glaciers over areas that have, before then, been ice-free. Most is known about the last ice age during the Pleistocene geological epoch 2 million years ago. However, geological studies show evidence of earlier ice ages although less is known about these.

Taken from Dictionary of Science

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The general term "ice age" or, more precisely, "glacial age" denotes a geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in an expansion of continental ice sheets, polar ice sheets and alpine glaciers. An ice age is a natural system. Within a long-term ice age, individual pulses of extra cold climate are termed "glaciations". Glaciologically, ice age implies the presence of extensive ice sheets in the northern and southern hemispheres; by this definition we are still in an ice age (because the Greenland and Antarctic ice sheets still exist).

Taken from Wikipedia