8 NEW YORK STATE MUSEUM 



knowledge concerning the lithology of the Adirondacks. It is not a 

 little interesting to note in the work cited interpretations which are 

 considerably at variance with those held by present-day geologists, 

 particularly in regard to the sedimentary origin of syenite (Em- 

 mons, 1842, page 80), and the igneous origin of the crystalline 

 limestones (Emmons, 1842, pages 38-59). These views are sug- 

 gestive of the uncertainty which beset the pioneers who dealt with 

 problems of genesis and relationships among the rocks of this appar- 

 ently chaotic Precambrian complex. But however much modern 

 ideas concerning the nature and origin of the numberless rock 

 types of this complicated area may differ from those entertained by 

 the predecessors and contemporaries of Emmons, the fact remains 

 that his work, though but the beginning, was a substantial found- 

 ation upon which much subsequent progress has been based. 



Twenty-three years elapsed before the publication of further ob- 

 servations on Adirondack geology, and during the quarter century 

 which followed, a period of scant activity in this region, only six 

 papers were added to the literature. These, with two exceptions, 

 were purely descriptive, and in so far as they dealt with the obser- 

 vational side of the subject, local in their scope. Thus Macfarlane 

 in the northwest, Leeds and Britton in the interior, and Julien in 

 the east, made material additions to the knowledge of their respec- 

 tive areas. Hunt and Hall, however, though more ambitious to 

 theorize from their observations, did so at a time when the facts in 

 hand afforded but an insecure basis for such generalizations, and 

 their interpretations were in some instances later superseded. 



The year 1891 ushered in a period of continuous and productive 

 progress in this field under the auspices of the State Survey, begin- 

 ning with the joint work of Professors Kemp, Smyth and Gushing, 

 followed by the continued labors of Gushing, which more recently 

 have been supplemented by those of Prof. W. J. Miller. These 

 observers, by the application of modern methods of investigation, 

 have solved the major problems of Adirondack geology. Van Hise, 

 who had already made a brief visit to the region in 1890 in company 

 with Pumpelly, Walcott and G. H. Williams, was the author of 

 the first broad theory regarding the structure of the Adirondacks as 

 a whole. His view (Van Hise, 1892, pages 399, 435) that the 

 heart of the mountains was an eruptive core of gabbro surrounded 

 by a fringe of various gneisses dipping quaquaversally, controlled 

 then, as to a slight extent it colors now, the commonly accepted 

 opinion in the matter. The later observations, however, have shown 

 a general tendency to drop away from the idea of a periclinal 



