PART I. 



INTRODUCTION TO THE STUDY OF THE UPPER 

 DEVONIAN OF NEW YORK STATE. 



Occurrence of Rocks. 



Where rocks are seen. — The casual observer notices clays, 

 sand and gravel along roads and in fields as he passes through 

 the country; he notes here and there a boulder, or a stream-bed 

 replete with flat stones, sees occasionally a quarry, a railroad cut, 

 or a precipitous river bank where large masses of rock are exposed 

 to view. Rarely does he stop to consider what these objects 

 really are or how they came to be where they are. The story in 

 each case is a long one, and this brief work will be limited chiefly 

 to the last-mentioned class, namely those seen in quarries or other 

 excavations, natural or artificial. 



Rocks everywhere; a hard lesson. — At the outset the learner 

 must grapple with and master one fundamental and all-important 

 fact, for unless his mind is perfectly clear on the subject he can 

 form no correct conception of what follows. The fact is this: 

 Though large masses of hard rock are usually observed only 

 where some natural or artificial digging has recently been going 

 on, they do exist everywhere though hidden from view by a 

 blanket of soft or loose earthy matter, like sands, soils and gravel. 

 In mountainous regions where there is no soil the rocks are 

 everywhere apparent, but in southern New York they are so 

 generally covered over and hidden that their presence is often 



