676 ABSTRACTS OF PAPERS 



Cretaceous formations, involving vertical displacements of 8,000 to 12,000 or 

 more feet. The horizontal displacement is estimated at not less than 12 miles, 

 while the zone of movement was probably as much as 35 miles wide. The fault 

 with its irregular trace extends at least 270 miles. 



Discussion 



Dr. Eliot Blackwelder : The Willard thrust in the Wasatch Mountains, 

 referred to by Mr. Mansfield as possibly part of the Bannock thrust, seems to 

 indicate movement of the overriding block from east to west. This is inferred 

 from the drag-folds underlying the thrust block. 



The announcement was made that in the Snake River Range Carboniferous 

 beds have been found in contact with the Cretaceous, suggesting a northward 

 continuation of the Absaroka fault; and also that there are overthrusts along 

 the southwest side of the Wind River Mountains, which were first noted by 

 C. L. Baker in 1909. On the Wind River thrusts the Archean overrides from 

 the northeast the Carboniferous and even Cretaceous. 



Mr. Mansfield was asked whether the warping of the Bannock thrust was 

 contemporaneous or subsequent. The reply was that the facts were not sug- 

 gestive on that point. 



ANGULAR UNCONFORMITY AT CAT SKILL 

 BY GEORGE H. CHADWICK 



(Abstract) 



Recent changes in the water level of Catskill Creek, New York, have brought, 

 to light new and striking evidences of the unconformity between Lower and 

 Upper Silurian (Champlainic-Ontaric) rocks. 



DISPLACEMENTS OF TRIANGULATION STATIONS IN SUMATRA DUE TO AN 

 EARTHQUAKE IN 1892 



BY HARRY FIELDIXG REID 



(Abstract) 



An earthquake occurred in Sumatra in 1S92 when the secondary triangula- 

 tion of the island was in course of execution. A number of survey stations 

 were displaced by the disturbance. All the displacements, both in amount and 

 direction, can be accounted for by assuming a horizontal slip on a fault similar 

 to that which occurred at the time of the California earthquake of 1906. 



SOME STRUCTURAL FEATURES IN THE NORTHERN ANTHRACITE COAL FIELD 



BY N. H. DARTOX 



(Abstract) 



In collecting data for constructing a contour map of the structure of the 

 northern anthracite coal basin many interesting details of structure revealed 

 by mining have been obtained. Some sections show marked irregularity in 



