212 
GEOLOGY OF THE FIRST DISTRICT. 
Europe, is more or less covered with a mantle of drift deposits, composed of boulders, blocks, 
pebbles, gravel, sand and clay, variously mingled together, or stratified in separate masses.* 
2. These materials, over most of the northern parts of the United States, and of the northern parts of 
Europe, are similar to rocks in place to the northward of their present positions.* Very many 
of them have been traced to their parent sources, by trains of evidence that are so strongly marked, 
in some instances, as to leave no doubt of the distance and direction of their transportation. 
3. These depositions preceded the alluvial, and were deposited at a later period than the tertiary. 
4. Heavy boulders and blocks of many hundred tons weight, as well as smaller ones and pebbles, are 
frequently intermingled with, or deposited on, beds of clay and sand. 
5. Broad and deep valleys, lakes, and arms of the sea, and hills and ranges of mountains of moderate 
height, intervene between the parent sources and the present resting places of much of this 
detritus. 
6. The boulders and blocks are sometimes scattered nearly uniformly over great extents of country; 
in other parts they are collected in nests or groups, great numbers being found on small areas, 
while in other parts around they are rare. 
7. These groups of boulders are not unfrequently seen on plains and in valleys, but they are more 
common on the sides of hills and mountains, or on the edges of the terraces. 
8. Great numbers of boulders and blocks are sometimes seen arranged in a nearly horizontal belt, fol¬ 
lowing all the sinuosities of the ground; but more numerous in the valleys along these belts than 
on the projecting points, as if they had lodged in and around bays, more abundantly than on 
the headlands. 
9. Gravel hills (containing boulders and blocks) somewhat peculiar in form and general aspect, cha¬ 
racterize the gravel deposits of drift in many parts of the northern district of the United States, 
and particularly in New-England and New-York.f 
10. Boulders and pebbles are often found in the situation in which they have been placed by natural 
causes, with their smoothed surfaces scratched in straight lines; and in some instances where 
there were hard portions on some parts of the worn surfaces, they seem to have protected a por¬ 
tion of the softer material, leaving it in a ridge behind each of them, and all parallel, as if the 
boulder had been dragged along in a fixed position over other hard bodies, which had worn 
away the softer parts, except those protected by the harder points. 
* The drift detritus has been examined from the Atlantic coast in Nova-Scotia, New-Brunswick, Maine and the East¬ 
ern States, to the Coteau de Prairie between the head of the Mississippi and the Upper Missouri, and found to present 
numerous evidences of transport from the north and northwest, with the exception of the high primary region between 
Lake Champlain and the Black river, and the St. Lawrence and Mohawk, from which boulders seem to have been dis¬ 
persed north, south, east and west, to great distances, and particularly to the south. In Europe, the direction of trans¬ 
portation seems to have been from the northeast and north-northeast, except around the Alps, from which boulders and 
blocks have been dispersed in every direction through the main valleys. The southern portions of the United States and 
Europe show few evidences of the transportation of heavy blocks and boulders. Few have been seen south of the Ohio 
or of the Lower Missouri; but gravel and small pebbles of northern rocks, with their characteristic minerals, have been 
observed as far south as Mississippi and Louisiana, where I have often seen them. 
t These hills are distinct in character from those at the embouchures at valleys, and which correspond to the bars at the mouths 
of rivers. Those referred to, are found in valleys, and on great extents of country of a nearly uniform general level. 
