NEW ENGLAND APPALACHIAN SYSTEMS 



165 



The manner of thrusting, as conceived by Kay, in map view is graphi- 

 cally illustrated in Fig. 11.12, and in cross section in Fig. 11.13. 



Two cross sections of the central and southern Taconic Range are pre- 

 sented in Fig. 11.9 and should be referred to in the following discussion 

 against the klippe hypothesis. 



In a study of the Taconic Range west of Troy, Ralk ( 1953 ) recognizes 

 thrusting and an eastern allochthonous sequence and a western autoch- 

 thonous sequence, but concludes that dense vegetation cover and much 

 drift leave so few outcrops that the existence of a great Taconic klippe 

 cannot be proved or disproved. In a study farther south near Pough- 

 keepsie (1937) he believes there is little evidence to support the thrust 

 and klippe hypothesis. 



Thrust sheets and klippen are postulated because of anomalous stratigraphic 

 successions, not otherwise explainable; or because of structure anomalies not 

 understandable from other points of view; or because the klippen, although 

 closely related to rocks nearer the root zones, were obviously out of their 

 proper geologic setting; or on the evidence of intensely crushed subhorizontal 

 zones of deformation; or on the evidence of exposed soles. None of these 

 criteria appears to be fully applicable here. There is no proof of an anomalous 

 stratigraphic succession in the gap of Wingdale; the deformation of the 

 supposed thrust sheet of pelite is, to all appearances, synchronous with that 

 of the autochthonous formations; the gneiss of the supposed klippen is known 

 to underlie the sedimentary rocks a few thousand feet below the surface; no 

 crush horizons, or exposures of indubitable soles, have been observed (Balk, 

 1937). 



Craddock (1957) also concludes against the major klippe hypothesis 

 (middle cross section of Fig. 11.9) in a study of the southern cud ol tin- 

 Taconic Range. He says: 



Fig. 11.12. Distribution of Canadian (Lower Ordovician) facies in New England and New 

 York, after Kay, 1942. The map on left shows the present distribution as a result of the 

 Taconic (post-Ordovician) thrusting, and the map on right shows the inferred distribution 

 before thrusting (a palinspastic map). Vertically ruled sediments are carbonates; horizontally 

 dashed sediments are shales. 



GREEN 



MT5. CONNECTICUT 



/? D/ROND^CM AXIS 

 Fig. 11.13. Section of Adirondack dome and Taconic system restored to early Silurian time (after Kay, 1942). 



AXIS 



BELT 



