4 NEW YORK STATE MUSEUM 



subsequently acquire one of them, and on a later occasion still another 

 was secured from the same source. Because of these facts the Scho- 

 harie section has become a basis of reference in studying these 

 faunas, and for 50 years past it has been a region freely visited by 

 students of geology ; and yet during all this time no geologic map 

 of the area has been published except on a very small scale in con- 

 junction with and as a part of the maps of the State as a whole. To 

 meet a definite want on the part of students, and for the more detailed 

 exposition of the geology of that region a map has been com- 

 pleted during the present season on the quadrangle scale which 

 covers the area from Middleburg northward to the south line of 

 Montgomery county. The work has been carried out by Prof. A. 

 W. Grabau, who has previously labored with much credit on similar 

 problems, and his map and report thereupon are presented in the 

 following pages. 



Structure of the disturbed fossiliferous rocks in the cement district 

 about Rondout. The lucid and A^ery interesting exposition of the 

 geology of Becraft mountain which was given in my last report 

 has led to a consideration of the rather more complicated region 

 of rocks of like age on the opposite or west side of the Hudson 

 river. B.ecraft mountain in Columbia county is the remotest 

 outlier of the series of rock beds which so extensively enter into 

 the composition of the Helderberg mountains of Albany county. 

 At Kingston, Hudson and eastward these rocks were caught in the 

 Appalachian folding, and subsequent erosion of these folds has iso- 

 lated the area at Becraft mountain entirely from the parent mass. 

 At Rondout and vicinity the rocks have been left in continuity, 

 but it has long been recognized that they are exposed under 

 much perplexity of form, due to the folding and displacement 

 of the beds. The structural problems presented there have 

 never been understood and as long- as geologic work has been car- 

 ried on in this State the situation in this region has been 

 somewhat timorously approached. These problems seemed to afford 

 features of much interest connected with the tectonics of the 

 region and the mode of the Appalachian disturbances, and the 

 fact was recognized that a solution would probably not be found 



