SIXTH REPORT OF THE DIRECTOR I909 1 57 



DOWNWARD OVERTHRUST FAULT AT SAUGERTIES, 



N. Y. 



BY GEORGE H. CHADWICK 



Canoe iiili, north of Saugerties village, Ulster co., is fepre- 

 sented on the Catskill toipograp'hiic sheet as a dumb-bell ridge with 

 the highway passing obHquely across the narrowed middle. It is 

 surrounded by clay plains of Lake Albany age, along which, on 

 the west and north of the hill, runs the West Shore Railway. The 

 Canoe ridge is a part of the range of Helderberg Hmestone hills, 

 known locally as the Kalkberg (pronounced collabarrack, — ''Collar 

 Back" of the map!), which here sags under the Albany clays, 

 its summits rising as a chain of islands out of the plain. 



During a recent visit to this hill in company with; the two gentle- 

 men named beyond, the writer was impressed by the occurrence 

 here of an overthrust almost identical with those in the Vlight- 

 berg at Rondout [see van Ingen & Clark. Disturbed Fossiliferous 

 Recks in the Vicinity of Rondout, N. Y. N. Y. State Mus. Bui. 

 69]. Although it seems likely that this fault has been observed 

 'by others, no reference to it now occurs to the writer, and a brief 

 account, with diagrams, is therefore presented because of the con- 

 spicuous nature of the faulting and the more ready accessibility of 

 the locality as compared with the Rondout faults. 



The locality is in the first hill northeast of Saugerties depot, 

 and not over a mile distant. The map [pi. i] shows the road 

 crossing the hill in the oblique valley determined by the fault. 

 The village stone crusher, located at the corporation line, fur- 

 nishes a conspicuous landmark for the visitor. Opposite this, 

 on the east, a blind road leads under the hill. V^arious quarries 

 and diggings [Q] add to the ease of study of the ledges which 

 are everywhere conspicuous. 



The rock at i, by the roadside as one turns into the crusher 

 quarry, is much brecciated and shot through with calcite seams. 

 It looks like upper Manlius, but no fossils were found. The 

 brecciation is probably due to its lying in the fault zone. At 2, 

 the cliff face behind the stone crusher, the limestone is hard, 

 blue and vertical, with calcite veins and geodes. The fossils are 

 Sieberella galeata, Favosites etc., of the Coeymans lime- 

 stone. Passing across the highway to 3, where the Manlius would 



