NJDEP - NJGS - First Annual Report of the Geological Survey of the ...

8ods of thousands of years, others for comparatively but ashort period. It is often askca during what length of timehave all of these successive changes taken place. But thegeologist can compute time only by comparison. That it musthave been inconceivably great, no one who studies the vastsedimentary deposits in which these remains are found beforeman appears upon the surface, and then e_rapares the timewhich was necessarily required in forming these deposits withthe time duri_ag which that portion of the earth's crust wasdeposited in which the remains and works of man are found,will fail to conclude that it is impossible to form an adecluateidea of its long duration.Having perfected and regulated,the order of succession inwhich these changes have taken place, the geologist, commencingwith the oldest aqueous rocks, reads the condition ofthe earth at that period, the state of the atmosphere and itstemperature, the changes which took place by aqueous and• volcanic agencies, and then, coming as it were to a chapter ofmore modern history, he reads of another period ; and thus,turning page aRcr page, examines successively the changeswhich have marked the earth's history daring a lapse of millionsof years.So regularly have these changes occurred over the'wholesurface of the earth, that the nature of the organic remains issufficient to determine the general character of the rocks, andthe period at whleh they were formed.Perhaps it may not be out of place here to remarlq for theinformation of many with whom I have conversed in differentparts of the State during the past year, and who entertained .an idea that the principal object in collecting fossils, or organicremains, was merely the formation of cabinets of curiosities atthe State capitol, and at the various county scats, at a large expenditureof the public money, that the organic remains foundin the rocks constitute the basis of economical geology. It isto them that many of the valuable discoveries in the aqueousrocks are due. The rescarehcs of Messrs. Conrad and Hall,.have been the means of placing the geology of this country onNEW JERSEY GEOLOGICAL SURVEY