54 NOTES AHTa 



and others are entirely so. These changes will proceed, and they maybe ascri- 

 bed to the following causes : 



1. The cutting down of the woods, and the draining of swamps, expose the 

 waters to the power of the sun, and dry up the sources from whence they 

 proceed. 



2. Cultivation increases the alluvions of rivers, etc. by loosening the soil, and 

 depriving it of the trees and plants which prevented it from being carried off by 

 the water. 



NOTE 8. 



The fossil shells and petrifactions which have been discovered all over the 

 world, on the loftiest mountains as well as in the bowels of the earth, are justly 

 considered as the most interesting phenomena of nature. Linnaeus says that, " the 

 innumerable petrifactions of foreign animals, and of animals never seen by any 

 mortal in our day, which often lie hid among stones under the most lofty moun- 

 tains, are the only remaining fragments of the ancient world." Buffon denomi- 

 nates them the monuments, and Pallas styles them the medals, of nature. Dr. 

 Barton has expressed this idea in the following impressive language : *' I consider 

 the petrifactions and impressions which are found on many of our mountains, as 

 some of the most interesting medals of the revolutions which our country has 

 undergone." 



This country furnishes these medals of nature in as great variety and abun- 

 dance as any in the world. They are found in a number of forms ; 1. The 

 fossil shell detached from any other substance ; 2. The real shell embedded in, 

 or adhering to, stone ; 3. The impressions on stone of the elevated and concave 

 Surfaces of the shells, without any vestige of them. 



Kalm made many interesting discoveries of petrifactions in the northern parts 

 of this state. On the mountains at Crown Point he found petrifactions of all kinds ; 

 .and chiefly pectinites, or petrified ostrea pectines ; and sometimes whole strata of 

 the latter, consisting merely of a quantity of shells of this sort grown together j 

 generally small, and never exceeding an inch and a half in length. Some of the 

 shells were very elevated, especially in the middle, where they formed, as it were, 

 a lump ; others again were depressed in the middle ; but in most of them the out- 

 ward surface was remarkably elevated, and the furrows always run longitudinally 

 from the top diverging to the margin. These petrifactions were principally found 

 in black limestone, lying in lamellae, as slates do, and might be called a kind of 

 slates convertible into quick lime by fire. The strata which lay uppermost in the 

 mountains, consisted of a gray limestone. The black liosestona is the marmor 



