CURRENT PRE-CAMBRIAN LITERA TURE 409 



differs in appearance from the older gneiss, and a considerable portion 

 seems to be unquestionably of sedimentary origin, although dynamic 

 nietamorphism has obscured all traces of clastic structure and given 

 the gneiss a foliation in common with the older gneisses, rendering 

 the field relations obscure. From Parishville westward to Potsdam the 

 Grenville series is more widely distributed, less faulted, and less 

 completely metamorphosed, and hence with its sedimentary character 

 less disguised, than the Grenville series farther east, probablv because 

 of its greater distance from the anorthosite intrusion. However, it 

 seems to be beyond question that the eastern and western series are 

 equivalent. 



3. The anorthosite intrusion. 



4. Later gabbros. 



5. Granitic intrusions. The region was then subjected to intense 

 dynamic nietamorphism, after which occurred the intrusion of 



6. Diabase and trachyte dikes. 



7. Paleozoic rocks overlying unconformably all the preceding. 

 Kemp 1 continues his preliminary report on the geologv of Essex 



county, N. Y., with an account of the detail geology of the individual 

 townships. The additional obs*ervations have corroborated the con- 

 clusions reached in his previous report on this county, 2 concerning 

 the main classification of the rocks of the area, although it is now 

 doubtful if a sharp stratigraphic distinction can be drawn between 

 Series (1) and (2). 



Kemp 3 describes and maps the geology of the Lake Placid region 

 in the Adirondacks of the northwest part of Essex county. Crystal- 

 line rocks of Algonkian age occupy a large part of the area. These 

 include crystalline limestone, quartzite, granite, gneiss, and anortho- 

 site. It is probable that some of the gneisses, and especially those 

 associated with the limestones and quartzites, are altered sediments, 

 and it is also probable that the gneisses with augen of labradorite are 

 squeezed igneous rocks, but the investigation does not permit of their 



1 Preliminary report on the geology of Essex county, by J. F. Kemp: From the 

 Fifteenth Ann. Rep. of the State Geologist, in Ann. Rep. of N. V. State Museum, 

 1895, PP- 579-614. With geol. maps. 



2 See Report of State Geologist of New York for 1893, pp. 433-572. Summarized 

 in Journal of Geology, Vol. VI., 1898, pp. 528-529. 



3Geology of the Lake Placid region, by J. V. K.EMP: Bull. N. V. State Museum, 

 Vol. IV., 1898, pp. 51-64. With geol. map. 



