Continental Drift and Plate Tectonics PDF

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98 Continental Drfft and Plate rccto11lr5 !1,,, 0 ,napJ mor/11 bJ We 1 ,, , f h1urt1 I J 1 1011 ;mdFuront'lut\ [ ),l\l'ltl \Iii Pll I 1IC ' lt',l\llllll\r r \.'.\\,\\tropht' ol l\Jt),\h\ nnnd , 1111 11ll I ~ st'l'l\\t\\ \t)l) t,\l 1t-11 ht-d r,,, s1 1, 111 111 r. r 2 publi1, ,,nd it"~' ft11w111r11, 111)1 111 f,l'lll'l,\l bl' It'\ 1, { 1\ f1'1 t;Q Ht\\~ I he tl1t llf) \\ I 1 th 111 fit , t \ N,,ia"rr1\ ,c, 1()\1\1~ '" 190s, "'""1111 P' \ nH t i1 ~n ului;1,1, l I ml, B 1 1) , p mltd < ut ~ numl,rt 1if 1,cplogii 1111 s that CO\lld t,r t''\l'\a11111t ln ((1111111c111 ii I', OI dn t 1l Hm, c, rr. \lf1c-d \\ i i;1 1H'', ,1 ~ , nhy,1ll\l e Genn,m mctC'1'll' I1,g,,1 ,\Ill b1 0 r JA J' J11 t 11 1,111 1 f912 Im publtch prr,r1tt1'11 111.1. j d a that Earth\ l.rnd1na~,c~ n11g1 ,lll', f Iis b," k. () 1gm of Contmcnt., md Occ,111s,.... \\' ,,,ciwr " ho 1s tod,1y pprmd m 191 · 1 ~. '. ~ f('garded a, the fa1he1 of this concept, J ~ti ba,ffi h1, theorv not onh on the shap:s of the continent~. but Jlso on geolo~1c e, dence ,uch as similarities in the foSSl~S found in Brazil. Africa, India, Australia and Anurctica. He drew a series of maps u shov.-in three stages in the drifting [) rocess" bevinnmg with an original large P ' :, ' b landmass. which he called 'Pangaea meanin "all lands".) Wegener believed J that the" continents, composed of light ti silic rocks (sial), somehow plowed ~ throu"'h the denser rocks of the ocean's 1 I) floor (Sima), driven by forces related to t the earth {Fig. 7.3). Wegener was drawn to the idea to explain the ancient climates of Alfred Wegener the past. The puzzling questions in his mind were: (i) \Vhy should tropical ferns have grown in London, Paris, Bonn and even in Greenland?, (ii) Why coal belts are found in the cold climatic regions, Pechora basin of the tundra?, and (iii) Why glaciers have covered part of Brazil, Peninsular India, Australia, South Africa, and the Con o basm at the same time? While thinking over the given points, the theory of continental drift grew out of the need of explaining the major vari.nions of climate in the past. The climatic ch,rnges on the e,1rth in the opinion of Wegener, may be explained in two ways: 1. Jf the continems remained s1ationa1 y ,ll their pl.Ke,, the dim.nic zones might have shifted from om region to.11101 her.  C""'""'" '"' lhlft 111111 rllll!l l111t1111l11 9 11 " , 11111111 , 11111 111111111r d I 11 d 11111111 11 1y, 11,, I I1 1vr I ,