140 GEOLOGY AND MINERALOGY. 



of Essex County, based on intimate personal study in the 

 field. 



Biit Mr. Crosby did not stop with this brief exposition. 

 He prosecuted his work in the field and laboratory, and 

 in 1880 published an octavo volume of two hundred and 

 ninety-five pages, with an accompanying map, entitled 

 "Contributions to the Geology of Eastern Massachusetts.'' 

 It appeared under the auspices of the Boston Society of 

 Natural History, with which he is officially connected. 



The volume is a worthy monument of years of careful 

 research and study, but its author disclaims any preten- 

 sions to completeness. In the nature of the case, it can- 

 not be exhaustive. Large tracts of rocks, thatare needed 

 to verify inferences, are covered by drift and water, and 

 future explorations and quarry-workings must be looked 

 to for the explication of some unsolved questions. 



It is hoped that an abslract of Mr. Crosby's report, with 

 a geological map of the county, will be published by the 

 Institute for the use of our schools and public libraries. 



My report has come to an end, but the work of which 

 it treats may be said to have been just begun, in a way 

 that will need no radical revision. It is a work to which 

 all observing, inquiring minds can contribute. 



The intelligent farmer in his fields, the teacher and her 

 scholars in their rambles, whoever has eyes to see, can 

 help the geologist to complete the story of creation written 

 on the great stone leaves of the earth's crust. The re- 

 wards of such work lie in the discovered facts, without 

 which man knows not all the beauties and riches of his 

 earthly home, and even the commonest life is not com- 

 plete. 



