marble

• limestone changed into

59:1.16The trilo­bite fos­sil-bear­ing strata of this epoch out­crop here and there through­out all the con­ti­nents ex­cept in cen­tral Asia. In many re­gions these rocks are hor­i­zon­tal, but in the moun­tains they are tilted and dis­torted be­cause of pres­sure and fold­ing. And such pres­sure has, in many places, changed the orig­i­nal char­ac­ter of these de­posits. Sand­stone has been turned into quartz, shale has been changed to slate, while lime­stone has been con­verted into mar­ble.

• limestone changed into

59:3.1300,000,000 years ago an­other great pe­riod of land sub­mer­gence be­gan. The south­ward and north­ward en­croach­ment of the an­cient Sil­urian seas made ready to en­gulf most of Eu­rope and North Amer­ica. The land was not el­e­vated far above the sea so that not much de­po­si­tion oc­curred about the shore lines. The seas teemed with lime-shelled life, and the falling of these shells to the sea bot­tom grad­u­ally built up very thick lay­ers of lime­stone. This is the first wide­spread lime­stone de­posit, and it cov­ers prac­ti­cally all of Eu­rope and North Amer­ica but only ap­pears at the earth’s sur­face in a few places. The thick­ness of this an­cient rock layer av­er­ages about one thou­sand feet, but many of these de­posits have since been greatly de­formed by tilt­ing, up­heavals, and fault­ing, and many have been changed to quartz, shale, and mar­ble.

• Carrara

60:1.4Over Eu­rope, es­pe­cially Ger­many and Rus­sia, may be found de­posits of this pe­riod. In Eng­land the New Red Sand­stone be­longs to this epoch. Lime­stone was laid down in the south­ern Alps as the re­sult of a sea in­va­sion and may now be seen as the pe­cu­liar dolomite lime­stone walls, peaks, and pil­lars of those re­gions. This layer is to be found all over Africa and Aus­tralia. The Car­rara mar­ble comes from such mod­i­fied lime­stone. Noth­ing of this pe­riod will be found in the south­ern re­gions of South Amer­ica as that part of the con­ti­nent re­mained down and hence pre­sents only a wa­ter or ma­rine de­posit con­tin­u­ous with the pre­ced­ing and suc­ceed­ing epochs.