272 XEW YORK STATZ M"SE . M 



prevaloice of Sihiric and Devonic strata, i. e. all strata abjve the 

 Hudson Rhrer slates. These strata have been a£Eected by only one 

 great moontain-msddng movement — that of the Appalachian fold- 

 ing, and minor disturbances of still later date. 



B Hudson river district. This includes that portion of the 

 region lying between the northern border of the Highlands and the 

 Shawangunk mountains. It is marked by the prevalence of Cam- 

 bric and Ordovidc strata, i. e. Hudson River slates, associated with 

 Wappinger limestone and Poughquag quartzite as the chief bed 

 rock. These strata have been affected not only by the Appalachian 

 folding but also by a still earlier one — that of the Green mountains 

 and the Taconic range. They were folded into mountain ranges 

 and worn down in part again before the Sihiric and Devonic strata 

 of district A were in existence. Therefore as a structural proUem 

 this district * B) is approximately twice as complex as the other. 



C Highlands district. This includes all of the region com- 

 monly known as :. e H ^ \ i- of the Hudson as well as tlie rest 

 of the area sou:': :: : r '' \ri- premier t? > f ^ Y :-'.■: :•- I:s 

 rocks are the olies: — : : : rst. Thty . . L z-. : - .zo 



mountain structures and in par: :. down before any of the 

 othei^ were accumulated. Th- t '■- '-^z^ii erctensive 



igneous intrusion so that in ; vt . -^ Trevail. 



.And besides they have been me: : t t 



of any other group. Xo other series :i s:ra:a ::as -«eeii - : - 

 foundly aff^ected- They form the lowest group. All things 

 sidered this district should be structurally three times as : 

 cated at the first one 1^^), and adding the igneous and me:' 

 complexities, it is probably more nesr the truth to ccr : _ : s 

 Higjiland district four or five tii::es t inp'.ex. 



All of Ae formations f re n : t : : :/- Millie P :.rz 



involved. Fcr the specific f ::: : - : - r::::ess:::: : : -- 



tie- the re^iT: - referrel :: : - ^ :^^ ::: ::: ;::: : V" : ; zx 

 et sc-q.]. 



Stmctural features 



Except the most westerly part of t::e re rim, that occupied by the 

 Upper DevcMiic strata, all formati compressed into folds- 



Many of the analler folds, especially : le in the Catddll district, 

 are still complete. The easy subdivision of strata possible in diis 

 district also siir; :£es : : of detecting small changes of 



altitude. But for : t '-^erer folds have been beveled 



off extensivelv bv s : - :it onlv the truncated limbs 



