]O GENERAL INTRODUCTION. 



the mighty Continental sea, previous to Paleozoic time. Its stern 

 Archaean shores were washed by the waves of countless ages before 

 the undermost strata of the Lower Silurian were deposited upon 

 them, entombing and preserving many of the Trilobites, Brachio- 

 pods, and other curious inhabitants of that vast ocean. This Lower 

 Silurian zone marked the shore line, so to speak, of the ancient 

 island, and consists of Potsdam sandstone and the lime rocks of 

 the Trenton period. Though broken and interrupted, enough of 

 it still remains to afford us tantalizing glimpses of the life of the 

 time, torn pages of fragmentary chapters that constitute but a half- 

 told story to excite our imagination and regret. 



The old Archaean centre, which we call the Adirondacks, is made 

 up mainly of gneiss, and includes areas of syenite, hypersthenite, 

 granite, iron ore, and other metamorphic rocks. The soil, therefore, 

 except that resulting from decomposed vegetation, is largely sili- 

 cious sand. 



3.-TOPOGRAPHY. 



The topography of the region is diversified, and in some respects 

 peculiar. The mountains and short ranges of high hills have no 

 regular trend, and conform to no definite axis. They are in no 

 sense a chain of mountains, and have no backbone at all ; but, on 

 the contrary, consist of more or less irregular groups, isolated 

 peaks, short ranges, and " hog-backs," scattered over the entire 

 area the highest to the eastward. They slope in all possible direc- 

 tions, according to the position and courses of the valleys and river 

 beds adjacent. Like the grand old Lawrentian Hills of Canada, 

 and other Archaean mountains, they are bold and rugged, with 

 well-defined and often much broken outlines. Nearly thirty peaks 

 exceed four thousand feet (1,219.20 metres) in height, several are 

 about five thousand (1,524 metres), and one, Mt. Marcy, attains an 



