Chester County and its people .. . ines are often bounded bysteep and rocky slopes. The northern boundary of this southerngneiss region is a line nearly straight, extending east-northeastand passing by West Chester. To the north of this line is a beltof hydro-mica-schist, and south of it spreads a country of syeniterocks, feldspar-porphyrj^ rocks, horneblendic gneiss, micaceousschists, chlorite-schists and quartzite beds. Over this region are tobe found patches of seiiDentine and crystalline limestone, beds ofimpure limestone, pure kaolin, and often an abundance of corun-dum. Accoiding to Prof
Chester County and its people .. . ines are often bounded bysteep and rocky slopes. The northern boundary of this southerngneiss region is a line nearly straight, extending east-northeastand passing by West Chester. To the north of this line is a beltof hydro-mica-schist, and south of it spreads a country of syeniterocks, feldspar-porphyrj^ rocks, horneblendic gneiss, micaceousschists, chlorite-schists and quartzite beds. Over this region are tobe found patches of seiiDentine and crystalline limestone, beds ofimpure limestone, pure kaolin, and often an abundance of corun-dum. Accoiding to Prof. Frazer these rocks were originally sedi-ments of mud, sand and gravel, their real stratification being visi-ble wherever they are quarried. Infinitely numerous and rapid variations of constituent char-acter, texture, hue and ciystalline contents make the study ofthese rocks difficult in a stiuctural sense. There areno key rocks to mark geological horizons, and so large a iiortion of ??- -*j^-.^~<ifTTTT„T;*. \VILLIA:\I WAYNE. AND ITf^ PEOPLE. 139 the uplaud is cultivated that the exposures along all the valleyscauuot be traced across and identified with those of another valleyonly a few miles distant. Without going into a detailed description of the various geo-logical formations, it may be stated that Prof. H. D. Eogers dividesthis southern gneiss region, which is now passing under review,into three belts, as follows: 1. A northern anticlinal, hard gneiss belt, on which WestChester stands. 2. A southern monoclinal, hard gneiss belt, on which Philadel-phia stands 3. The middle synclinal, soft gneiss and mica-slate belt, sep-arating the other two belts. The prevailing varieties of the northern belt of the southerngneiss region are as follows: 1. Massive feldspathic gneiss, some of it micaceous, some ofit like stratified syenite, sometimes porphyroidal, and very muchlike that at the falls of the Schuylkill. Dark, hard, hornblendicfeldspar gneiss, thinly lamina
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Keywords: ., bookcentury1800, bookdecade1890, bookidchestercount, bookyear1898
