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Drift material, loose material left on the surface by a retiring glacier, plays a part in wells and springs. (a) Beds of clay variously disiposed in a mass of sandy materials. (b) Wells sunk in different situations, and finding a supply of water only when a bed of clay is reached. A well on top of a hill may be shallower than one at the foot. (c) The surface of the earth. (d) Outcrop bed of clay, causing a spring. If the porous materials contain fragments of limestones, these spring waters are hard, and d. A well carried below its supplying-bed may lose its water again.

Phenomena of Wells and Springs in Drift Material

Drift material, loose material left on the surface by a retiring glacier, plays a part in wells and…

Diagrams showing the origins of eskers. A) A tunnel under the ice, nearly filled with sand and gravel by the subglacial stream which built up its bed to the level of the outlet. B) The same deposit after the ice melting of the supporting ice walls. Slumping has produced the characteristic steep side slopes.

Origin of Eskers

Diagrams showing the origins of eskers. A) A tunnel under the ice, nearly filled with sand and gravel…

Section of an old glacial pot-hole filled with debris, Christiana.

Glacial Pot-Hole

Section of an old glacial pot-hole filled with debris, Christiana.

Glacier descending into the sea, where its front is buoyed up by the water and becomes broken up into icebergs.

Glacier

Glacier descending into the sea, where its front is buoyed up by the water and becomes broken up into…

A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow. Glacier ice is the largest reservoir of fresh water on Earth, and second only to oceans as the largest reservoir of total water.

Glacier

A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow. Glacier ice is…

Diagram of a mountain region from which the former glaciers have melted away, leaving the cirques to testify to their former presence. Some of the cirques diverge, leaving a broad rounded ridge between them, others converge, being separated only by a serrated knife-edge or arete.

Glacier Mountain Range

Diagram of a mountain region from which the former glaciers have melted away, leaving the cirques to…

Moraine covered border of Malaspina Glacier from Blossom Island.

Malaspina Glacier

Moraine covered border of Malaspina Glacier from Blossom Island.

Diagram to illustrate the relationship of main and tributary glaciers. The surfaces of the two glaciers are in accord, but the valley of the main glacier is deepened much below that of the tributary glacier.

Glaciers

Diagram to illustrate the relationship of main and tributary glaciers. The surfaces of the two glaciers…

Floating iceburg, showing the proportion of visible to submerged ice.

Iceburg

Floating iceburg, showing the proportion of visible to submerged ice.

Diagrams to illustrate the mode of formation of kettle holes in glacial deposits.

Formation of Kettle Holes

Diagrams to illustrate the mode of formation of kettle holes in glacial deposits.

Valley of the Lauterbrunnen, Switzerland. A typical U-shaped glaciated valley.

Lauterbrunnen

Valley of the Lauterbrunnen, Switzerland. A typical U-shaped glaciated valley.

Limestone polished, furrowed, and scratched by the modern glacier of Rosenlaui, Switzerland.

Limestone

Limestone polished, furrowed, and scratched by the modern glacier of Rosenlaui, Switzerland.

Diagrammatic section of the Marjelen Lake, the Aletsch Glacier which holds it and the valley of the Viesch into which it drains when full.

Marjelen Lake

Diagrammatic section of the Marjelen Lake, the Aletsch Glacier which holds it and the valley of the…

Section of glacier lake called the Marjelen See.

Marjelen See

Section of glacier lake called the Marjelen See.

Crest of northern frontal moraine, looking northwest.

Frontal Moraine

Crest of northern frontal moraine, looking northwest.

Section of frontal moraine on side of Warner Street, Glouchester, Massachusetts.

Section of Frontal Moraine

Section of frontal moraine on side of Warner Street, Glouchester, Massachusetts.

In the valley glaciers, the rock fragments falling upon the ice from the valley sides, or sliding down in avalanches, accumulate upon the side of the ice, and as the glacier moves a long, such accumulations are strung out in lines of drift along the margin. This constitutes a lateral moraine.

Lateral Moraine

In the valley glaciers, the rock fragments falling upon the ice from the valley sides, or sliding down…

Where two glacial streams unite, their adjoining lateral moraines become confluent and are continued as a medial moraine.

Medial Moraine

Where two glacial streams unite, their adjoining lateral moraines become confluent and are continued…

Bird's eye view of about 2 square miles of terminal moraine. Lakes shown by horizontal shading; swamps are dotted.

Terminal Moraines

Bird's eye view of about 2 square miles of terminal moraine. Lakes shown by horizontal shading; swamps…

Rounded rock surfaces or <em>Roches Mountonnees</em>, due to erosion by a former glacier, Colorado.

Roche Mountonnee

Rounded rock surfaces or Roches Mountonnees, due to erosion by a former glacier, Colorado.