REPORT OF THE DIRECTOR AND STATE GEOLOGIST ill 



penetrated by a complex assemblage of granites and granite- 

 gneisses, which, though closely related, belong to at least two 

 different periods of intrusion. Stilt later dikes of diabase mark 

 the close of igneous activity, all of which occurred during the 

 pre-Cambrian. The results of the season's work are perfectly in 

 harmony with the conclusions drawn from earlier studies else- 

 where 1 in the crystalline area, and several localities were found 

 which afford information of great value as standards of com- 

 parison. 



The Potsdam was studied only in its relation to the crystallines, 

 and the conclusion was reached that the sandstone was de- 

 posited on an uneven surface, analogous to the present surface 

 of the crystallines. 



Till four years ago comparatively little work had been done in 

 the vast area of the Adirondack wilderness. The geologic 

 boundaries could not be definitely drawn, and the classified state- 

 ments were of questionable accuracy and in many cases out o£ 

 date. To map this area with some degree of practical accuracy 

 seemed one of the most pressing pieces of work and of very great 

 value in both pure and economic geology. The study of this field 

 was begun in 1892 at the request of the writer by Prof. J. F. 

 Kemp and published in the 48th report of the state museum. 

 Subsequently the field was in a measure divided between Prof. 

 Kemp, Cushing and Smyth under the direction of Prof. James 

 Hall. Of the particular detailed work of the past summer, the 

 three observers in the field have prepared individual reports 

 which are outlined above and are given in full in the following 

 pages. The work of the three preceding years has already been 

 published in the reports of Prof. James Hall. 



Economic geology 

 In economic geology, my assistant, Dr Heinrich Ries, has com- 

 pleted his revision 1 of the report on Clay industries, published in 

 1891, and has spent a part of the field season in preparing 

 material for the publication of a report on lime and cement. 2 This 

 report has long been needed, and will be of much value to the 



*See N. Y. state museum. Bui. 35. 

 2 See X. Y. state museum. Bui. 44. 



