SOUTHERN AND CENTRAL APPALACHIANS 



105 



ERIE, PA. PA 



N.Y. 



WARREN, PA. PORTAGE, N.Y. NAPLE5 



WATKINS GLEN BINGHAMPTON 



CAT5KILL MT5. 



Ham ilton gr. 

 ' ' h 



Onondaga /j /* 



0r/sX 



any 



/) snoK an 



Fig. 8.8. Upper cross section, the great Catskill delta from Erie, Pa., to the Catskill Mountains, 

 N.Y. After Schuchert, 1924. 



Black is black shale and white is conglomerate, sandstone, shale, and calcareous shale. The 

 elastics are dominantly red and generally coarsest in the eastern part. Vertical scale much ex- 



ward almost the entire belt is one of anticlines and synclines. See section 

 29, Fig. 8.20. They veer markedly eastward in central and eastern Penn- 

 sylvania, and by southern New York both the gently folded belt and most 

 of the strongly folded belt die out. The folds, if projected, would run 

 into the Adirondack uplift and the lower Hudson Valley. A narrow eastern 

 zone of the folded and thrust-faulted Appalachians, which is intimately 

 connected with the Rlue Ridge province, extends up the Hudson Valley. It 

 seems very crowded between the Adirondacks and the New England 

 metamorphic masses. See section 30, Fig. 8.21. 



As far as the folded and thrust-faulted Appalachians are concerned, 

 and aside from the narrow belt up the Hudson, it can be said that they 

 begin in southern New York in gentle folds and become stronger south- 



Onona'aga J 



Or/5Hony i fte/a"., r Decker 



aggerated. Thickness may be judged by reference to the isopach map of Fig. 8.9. 



Lower cross section, the Catskill Mountains and Hudson Valley north of Kingston, N. Y., after 

 Chadwick and Kay, 1933. It shows the present eastern erosional termination of the Catskill 

 delta, and presents the relations concerned with the problem of the source highlands. 



ward. Thrust faults appear and become the dominant structure in the 

 southern Appalachians. Also, in general, it can be said that the intensity' 

 of deformation across the belt becomes greater toward the southeast, 

 and in the Great Valley and at the Blue Ridge front it is the greatest. 



Regarding metamorphism, Keith (1923) pointed out long ago that a 

 distinct change in constitution of the strata occurs along the eastern 

 margin of the Valley and Ridge province in the Great Valley, and in the 

 adjacent Blue Ridge. Shales have taken on a slatv character, limestones 

 and dolomites are somewhat marmorized, and sandstones are quartzitic. 

 The slate belt of northeastern Pennsylvania and southeastern New York 

 in the tightly appressed and narrow belt of deformation east of the Blue 

 Ridge is well known. The change from bituminous to semibituminous to 



