AMERICAN GEOLOGY — MACLUREAN ERA, 1785-1819. 221 



tion on the .sides of many mountain ranges, with his Transition rocks. 

 To the Transition beds he evidently referred all the crystalline lime- 

 stones and dolomites (marbles) of western New England and the 

 Southern States, tog-ether with quartzites and gray waekes. The roof- 

 ing slates, now regarded as of Cambrian and Silurian ages, he classed 

 as secondary. The line between the Primitive and Transition may 

 "perhaps be marked b}^ the presence or absence of organic remains. 

 or of aggregates of rounded particles the result of former decomposi- 

 tion, in part, by the more or less crystalline texture and its approach 

 toward deposition. 1 " 



To the northwest of the Transition belt lies an immense area of sec- 

 ondary rocks, comprising, as above noted, the horizontal limestones and 

 slates skirting Lake Champlain about Ticonderoga and Crown Point. 

 There are also "immense beds of secondary limestones, of all shades 

 from a light blue to black, intercepted in some places by extensive 

 tracts of sandstone and other secondary aggregates, 1 ' which "appear 

 to constitute the foundation of this formation, on which reposes the 

 great and valuable coal formation, 11 which "extends from the head- 

 waters of the Ohio in Pennsylvania, with some interruption, all the 

 way to the waters of the Tombigbee. 11 He noted that along the south- 

 east boundaries of this formation, as on the fork of the Holston in 

 Virginia and in Greene County and the Pigeon River region of Ten- 

 nessee, gypsum, salt licks, and salt springs had been discovered. In 

 his first map this is indicated by a line of green extending northeast 

 and southwest entirely across the State. In the second he continues 

 it northeast to New York. The continuation of these as far north as 

 Lake Oneida, in New York State, led him to the conclusion, since 

 abundantly verified, that "we may hope one da} r to find an abundance 

 of those two most useful substances (salt and gypsum), which are 

 generally found mixed or near each other in all countries that have 

 hitherto been carefully examined. 11 He called attention to the pres- 

 ence of iron pyrites in the coal and limestone, of iron ores consisting 

 principally of brown sparry and clay iron stone, and of galena in the 

 Mississippi valley. On the Great Kanawha, near the mouth of Elk 

 River, he noted the presence of ""a large mass of black (I suppose 

 vegetable) earth, so soft as to be penetrated by a pole 10 or 12 feet 

 deep. Out of the hole so made frequently issues a stream of hydrogen 

 gas, which will burn some time;' 1 and he queried "if a careful exami- 

 nation of this place would not throw some light on the formation of 

 coal and other combustible substances found in such abundance in this 

 formation. 11 The occurrence of large detached masses of granite over 

 an area from Harmony, in Indiana, to Erie, New York, and thence to 

 Fort Ann, in some cases at least 200 miles from any known outcrops, 

 was noted, but no suggestion made relative to their probable means of 

 transportation. 



