428 THE POPULAR SCIENCE MONTHLY. 



not to be adequately shown by this brief statement. For, besides 

 generating habits of thought appropriate to the study of the Social 

 Science, it furnishes the mind with special conceptions which serve as 

 keys to the Social Science. The Science of Life yields to the Science 

 of Society certain great generalizations without which there can be 

 no Science of Society at all. Let us go on to observe the relations of 

 the two. 



+** 



FOOTPRINTS IN THE ROCKS. 



By CHARLES H. HITCHCOCK, A. M., 



PROFESSOR OF GEOLOGY IN DARTMOUTH COLLEGE. 



SEVENTY years ago, a student belonging to Williams College, 

 while holding the plough in his father's field at South Hadley, 

 Massachusetts, turned over a flat slab of sandstone about three feet 

 long. His attention was directed to what seemed to be a row of bird- 

 tracks upon its surface. He had often noticed as has every intelli- 

 gent person the impressions made by the feet of animals in the mud, 

 upon the shores of rivers, lakes, and in the highway. But he had 

 never before seen the imprint of an animal's foot upon the solid rock, 

 and had been taught to believe that the ledges were suddenly called 

 into being by the Almighty without passing through a tedious formative 

 process. Here, however, was a phenomenon not to be explained in 

 accordance with the popular opinion real footprints in the solid rock 

 and how came they there ? 



It was before the days of much geological knowledge, but Pliny 

 Moody exercised a common-sense method of explaining what he saw ; 

 for he concluded that these markings were made by some animal in 

 an early period of the earth's history. Nothing was more natural to 

 him than to surmise that they were made during the earliest aqueous 

 deposit of which he had heard the muddy sediments left by the 

 Noachian Deluge. Hence he pointed out these foot-marks to his 

 friends the specimen being utilized for a stepping-stone at his front- 

 door as having been made by Noah's raven when wandering in search 

 of dry land. The slab is still preserved, and the impressions appear 

 to have been made by one of that remarkable group of animals which 

 abounded in New England during the Triassic or New Red Sandstone 

 period. 



Thirty-five years later, as Mr. W. W. Draper, of Greenfield, a village 

 thirty miles farther north, was returning home from church, his atten- 

 tion was arrested by the sliding of snow from some large paving- 

 stones leaning against a fence. As he turned his eyes, he saw a row 

 of apparent ornithic impressions on the slab, shown very distinctly on 

 account of the reflection of the sun's rays from a wet surface. A 



