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according action advance Alps already amount angular appear basin become beds beneath blocks boulder clay called climate coast comparatively considerable containing course covered débris deposits descend difference difficulties direction distance district Drift Edition elevation England erratics evidence existence extend facts fall feet former fragments Geol geologists Glacial Epoch glaciers Glen gravel greater Greenland ground height higher hills hypothesis ice-sheet important indicate instance islands lakes land larger latitude latter length less lower lowlands marine marked mass material mean mentioned miles moraine mountain nearly neighbourhood northern numerous occasionally occur origin parallel pass places present probably produce Professor range reach regard region ridges rise river rock sand Scotland sea-level seems seen showing side similar slope snow sometimes southern stones streams supposed surface temperature thickness traced upper valley vary Wales western whole yards
Página 59 - It was a beautifully clear evening, and we had a most enchanting view of the two magnificent ranges of mountains, whose lofty peaks, perfectly covered with eternal snow, rose to elevations varying from seven to ten thousand feet above the level of the ocean. The glaciers that filled their intervening valleys, and which descended from near the mountain summits, projected in many places several miles into the nea, and terminated in lofty perpendicular cliffs.
Página 75 - ... thus building up their channels and obstructing the outlets of the tunnels. The blocking of the tunnels must cause the subglacial streams to lose force and deposit sand and gravel on the bottom of their channels ; this causes the water to flow at higher levels, and coming in contact with the roofs of the tunnels, enlarges them upwards ; this in turn gives room for additional deposits within the ice as the alluvial cones at the extremities of the tunnels grow in height. In this way narrow ridges...
Página 59 - The glaciers that filled their intervening valleys, and which descended from near the mountain summits, projected in many places several miles into the sea, and terminated in lofty perpendicular cliffs. In a few places the rocks broke through their icy covering, by which alone we could be assured that land formed the nucleus of this, to appearance, enormous iceberg.