glaciers

59:6.6Grad­u­ally the in­land lakes and seas were dry­ing up all over the world. Iso­lated moun­tain and re­gional glaciers be­gan to ap­pear, es­pe­cially over the South­ern Hemi­sphere, and in many re­gions the glacial de­posit of these lo­cal ice for­ma­tions may be found even among some of the up­per and later coal de­posits. Two new cli­matic fac­tors ap­peared—glacia­tion and arid­ity. Many of the earth’s higher re­gions had be­come arid and bar­ren.

64:1.4These events oc­curred dur­ing the times of the third glacier, the first ac­cord­ing to the reck­on­ing of ge­ol­o­gists. The first two glaciers were not ex­ten­sive in north­ern Eu­rope.

64:4.5In these times the Siberian glacier was mak­ing its south­ern­most march, com­pelling early man to move south­ward, back to­ward the lands of his ori­gin. But the hu­man species had so dif­fer­en­ti­ated that the dan­ger of fur­ther min­gling with its non­pro­gres­sive simian rel­a­tives was greatly less­ened.

57:8.22With this in­crease in land el­e­va­tion the first cli­matic dif­fer­ences of the planet ap­peared. Land el­e­va­tion, cos­mic clouds, and oceanic in­flu­ences are the chief fac­tors in cli­matic fluc­tu­a­tion. The back­bone of the Asi­atic land mass reached a height of al­most nine miles at the time of the max­i­mum land emer­gence. Had there been much mois­ture in the air hov­er­ing over these highly el­e­vated re­gions, enor­mous ice blan­kets would have formed; the ice age would have ar­rived long be­fore it did. It was sev­eral hun­dred mil­lions of years be­fore so much land again ap­peared above wa­ter.

61:2.335,000,000 years ago marks the be­gin­ning of the age of pla­cen­tal-mam­malian world dom­i­na­tion. The south­ern land bridge was ex­ten­sive, re­con­nect­ing the then enor­mous Antarc­tic con­ti­nent with South Amer­ica, South Africa, and Aus­tralia. In spite of the mass­ing of land in high lat­i­tudes, the world cli­mate re­mained rel­a­tively mild be­cause of the enor­mous in­crease in the size of the tropic seas, nor was the land el­e­vated suf­fi­ciently to pro­duce glaciers. Ex­ten­sive lava flows oc­curred in Green­land and Ice­land, some coal be­ing de­posited be­tween these lay­ers.

61:5.1By the close of the pre­ced­ing pe­riod the lands of the north­east­ern part of North Amer­ica and of north­ern Eu­rope were highly el­e­vated on an ex­ten­sive scale, in North Amer­ica vast ar­eas ris­ing up to 30,000 feet and more. Mild cli­mates had for­merly pre­vailed over these north­ern re­gions, and the arc­tic wa­ters were all open to evap­o­ra­tion, and they con­tin­ued to be ice-free un­til al­most the close of the glacial pe­riod.

61:5.2Si­mul­ta­ne­ously with these land el­e­va­tions the ocean cur­rents shifted, and the sea­sonal winds changed their di­rec­tion. These con­di­tions even­tu­ally pro­duced an al­most con­stant pre­cip­i­ta­tion of mois­ture from the move­ment of the heav­ily sat­u­rated at­mo­sphere over the north­ern high­lands. Snow be­gan to fall on these el­e­vated and there­fore cool re­gions, and it con­tin­ued to fall un­til it had at­tained a depth of 20,000 feet. The ar­eas of the great­est depth of snow, to­gether with al­ti­tude, de­ter­mined the cen­tral points of sub­se­quent glacial pres­sure flows. And the ice age per­sisted just as long as this ex­ces­sive pre­cip­i­ta­tion con­tin­ued to cover these north­ern high­lands with this enor­mous man­tle of snow, which soon meta­mor­phosed into solid but creep­ing ice.

61:7.1Through­out the glacial pe­riod other ac­tiv­i­ties were in prog­ress, but the ac­tion of the ice over­shad­ows all other phe­nom­ena in the north­ern lat­i­tudes. No other ter­res­trial ac­tiv­ity leaves such char­ac­ter­is­tic ev­i­dence on the to­pog­ra­phy. The dis­tinc­tive boul­ders and sur­face cleav­ages, such as pot­holes, lakes, dis­placed stone, and rock flour, are to be found in con­nec­tion with no other phe­nom­e­non in na­ture. The ice is also re­spon­si­ble for those gen­tle swells, or sur­face un­du­la­tions, known as drum­lins. And a glacier, as it ad­vances, dis­places rivers and changes the whole face of the earth. Glaciers alone leave be­hind them those tell­tale drifts—the ground, lat­eral, and ter­mi­nal moraines. These drifts, par­tic­u­larly the ground moraines, ex­tend from the east­ern seaboard north and west­ward in North Amer­ica and are found in Eu­rope and Siberia.