ON THE GEOLOGY OF THE TTNlTEI) STATES. 
the greater portion have only been so far investigated, that an 
outline map of the distribution of the general class of strata is 
all that can be attempted with any degree of fidelity ; but in this 
we have no cause for complain t, as_, when geological research 
shall have laid down more accurate data for the construction of 
charts, with exactitude, a reference to those which we now pub- 
lish, and such as will be found in future years in our pages, as 
an evidence of investigation and research, will prove the progress 
of geology in the intermediate period, and, also, the value of the 
records contained from time to time in our pages. We find that 
little was effected in the study of the geology of the United 
States before the year 1817, when Mr. Maclure submitted an 
interesting essay on the subject to the American Philosophical 
Society, the exactitude of which has been proved by subsequent 
researches, and which may, therefore, be said to form an excel- 
lent foundation for the study of American geology. 
The peculiar structure of the continent of North America by 
the extended continuity of the immense masses of rocks of the 
same formation or class, vnth the uniform structure and regula- 
rity of their uninterrupted stratification, forces the observer's at- 
tention to the limits which separate the great and principal 
classes ; on the tracing of which he finds so much order and re- 
gularity that the collection of the facts present somewhat the 
delusion of theory. 
The prominent feature of the eastern side of the North Ame- 
rican continent, is an extended range of mountains running 
nearly north-east and south-west, from the St. Lawrence to the 
Mississippi, the most elevated parts as well as the greatest mass 
of which consists of primitive as far south as the Hudson River, 
decreasing in height and breadth as it traverses the state of New- 
Jersey. The primitive occupies but a small part of the lower 
country, where it passes through the states of Pennsylvania and 
Maryland, where the highest part of the range of mountains 
to the west consists of transition, with some intervening vallies 
VOL. II. NO. XV, H 
