304 Exploring Visits to the Sources of the Hudson. 
stratified gneiss. ‘This labradoritic formation commences at the 
valley of the Schroon river, and extends westerly into the counties 
of Hamilton and Franklin, to a limit which is at present unknown. 
Its northern limit appears to be at the plains which lie between the 
upper waters of the Au Sable and Lake Placid, and its southern 
boundary which extends as far as Schroon, has not been well de- 
fined. It appears probable that it comprises an area of six or eight 
hundred square miles, including most of the principal mountain 
masses in this part of the state. So far as is known to the writer, 
no foreign rocks or boulders of any size or description are found in 
this region, if we are not to except as such, the fragments of the 
dykes, chiefly of trap, by which this rock is frequently intersected. 
The surface of the rock where it has been long exposed to the 
weather, has commonly a whitened appearance, owing to its exter- 
nal decomposition. Blocks and boulders of this rock are scattered 
over the country in a southerly and westerly direction, as far as the 
southern boundary of the state, as appears from the Report of Pro- 
fessor Emmons* and other observations, and they are often lodged on 
the northern declivity of hills, high above the general level of the 
country. ‘The most eastern of these transported boulders known 
to the writer, is one of about one hundred tons weight, at Cocksackie, 
on the Hudson, one hundred and thirty miles south from the labra- 
doritic mountains. This block is found on a hill, three hundred feet 
above the river, and one hundred and fifty feet above the general 
level of the adjacent country. 
First Expedition to the Mountains —Encampment. 
It has been noticed that the north branch of the Hudson, after 
its exit from Lake Sanford, joms the main branch of the river, 
about seven miles below the settlement at McIntyre. Having 
prepared for an exploration up the latter stream, we left MelIn- 
tyre on the 17th of July, with three assistants, and the neces- 
sary equipage for encampment. Leaving the north branch, we 
proceeded through the woods in a southeasterly direction, passing 
two small lakes, till, at the distance of three or four miles from 
the settlement, we reached the southern point of one of the moun- 
tains, and assuming here a more easterly course, we came, about 
noon, to the main branch of the river. ‘Traces of wolves and 
* Geological Report, p, 110. 
