Lyall Watson – The Water Planet

There have been [many] ice ages, four it seems in all, lasting around 100,000 years, during which ice accumulated at the poles and on higher plateaus.  Some of it simply grew until, in places, it was  over a mile deep, weighing down the land, compressing the earth'’ crust with burdens from which it continues to rebound.  Areas in Sweden are still rising in relief at a rate of half an inch a year.  But other parts of the great ice caps also started to flow, changing from static blocks to frozen rivers that spread out over the world, creeping down valleys and into warmer lands

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Next to convulsions in the planet’s crust, ice has done more to change the face of the earth than any other agency.  It has reversed the course of rivers, created and destroyed great lakes, changed the direction of evolution and shifted the boundaries between land and sea