20 GENERAL PRINCIPLES. 



Now we find in descending into the stratified rocks that they abound in fossils to the 

 depth of at least ten miles, and these are called fossiliferous ; but in all the rocks below, 

 which are mostly crystalline, of unknown thickness, no organic remains occur, and these 

 are called unfossiliferous. Neither do they occur in the unstratified rocks. 



The adjoining section of a portion of the earth's crust will give a better idea than verbal 

 description, of the relative position of the stratified and unstratified rocks of the fossil- 

 iferous and un-fossiliferous, of their thickness in Europe, of the relative position of the 

 unstratified and the stratified, and the names of the principal Formations and Groups in 

 both classes. Such a section cannot indeed be found at any one locality, but all the facts 

 are obtained at different localities and here combined into one view. 



SURFACE GEOLOGY. 



Surface Geology embraces those erosions of the earth's surface which have taken place 

 since the consolidation of its crust, and all those depositions of the abraded materials 

 which have taken place since the tertiary period. The amount of this erosion by the 

 ocean, the rivers, icebergs, glaciers, rains and the atmosphere, has been immense, exceed- 

 ing in some parts of Great Britian, 10,000 feet, and not less probably in our country. 

 The materials worn off before the tertiary period have been mostly consolidated into the 

 Palaeozoic, Mesozoic, and Kainozoic rocks : but since that period they have been spread 

 over the valleys and cavities as loose deposits. 



The earliest of these post-tertiary deposits were generally very coarse and scarcely 

 stratified, having been carried from high latitudes towards the equator, and are called 

 Drift. Subsequently a part of this drift has been acted upon by ice and water, more or less 

 comminuted, and re-deposited with a more distinctly stratified and laminated arrangement 

 upon the drift. This is called modified drift. Genuine drift, however, has continued to 

 be produced by icebergs, glaciers, mountain slides, and rivers, up to the present time. 

 But the period immediately succeeding the tertiary was the time of its most abundant 

 production, and has, therefore, received the name of the Drift Period. The formation is 

 mainly an earlier member of Alluvium. 



Drift and Modified Drift form some of the most striking and interesting features in the 

 geology of Vermont. 



PALEONTOLOGY. 



Paleontology is the science of fossils, or organic remains. It opens a marvellous history 

 of the ancient races and peculiar forms of animals and plants that once lived on the 

 globe. A few statements only of the leading conclusions of the paleontologist can here 

 be given. 



1. The number of species of animals and plants dug out of the rocks and described up 

 to the present time, cannot be less than 35,000, 2750 of which are plants. In 1849 Dr. H. 

 G. Bronn gave a catalogue of 26,421 species of animals and plants, distributed through 

 the formations as follows : 



