Remarks on American Rock Formations. 255 



mass, and our former ignorance of tfie true position of the 

 shells, have been the sources of our erroneous views. 



The second error of American geology, is the extending 

 or covering of the western country, and the back and upper 

 parts of New York, with secondary rocks. It was taken for 

 granted, that all horizontal rocks are secondary, and as the 

 rocks of these parts of the United States are horizontal in 

 their position, so they were supposed to be secondary ; and 

 as such are copied by every writer 1 am acquainted with. 

 With those writers, who do not admit a transition or inter- 

 mediate class, the generalization of inclination, and no in- 

 clination is admissible ; but is not so, when a transition class 

 forms a part of the system. This class, (the transition,) is 

 formed of mechanical particles, and nothing is more certain 

 than the tendency of such particles, when undisturbed, to 

 form horizontal layers or masses. It is also certain that an 

 uplifting or downfalling force, or both, have existed ; but it 

 is not certain that either or both these forces have acted in 

 a uniform manner, giving the same or nearly the same incli- 

 nation to rocks of the same age, and to every part of the 

 same rocks. These two suppositions are to be admitted, 

 before the characters drawn from inclination can be general- 

 ized, as has been done by Mr. Maclure. 



Innumerable are the facts, which have fallen under my 

 observation, which show the fallacy of adopting inclination 

 for the character of a class, and the geological boundaries of 

 the two classes in question, in the United States, abound in 

 such facts. Those rocks are highly inclined, whose proto- 

 types are horizontal towards the west, or otherwise removed 

 from the mountain range. The analogy or identity of rocks 

 I determine by their fossils in the first instance, and their 

 position and mineralogical cJiaracters in the secorid or last 

 instance. One observation, and then I shall terminate this 

 part, with the facts observed in the western country and in the 

 state of New York, which place certain rocks in a more ad- 

 vanced geological period, than has been ascribed or given to 

 them. It appears from what I have been able to observe, 

 that where the primitive or even the first transition rocks, ex- 

 ist as mountain or level ranges, those rocks, which are not 

 nearer than the bituminous coal depositions resting upon 

 them, are usually more or less inclined ; but if the primitive 

 be far removed from such rocks, no rule can be given ; thev 

 may be horizontal or inclined. Also, the greater the extent 



