AMERICAN GEOLOGY DECADE OF 1830-1839. 311 



debacles of water,' 1 the like of which can not be produced by any 

 causes now in operation. 

 Concerning the origin of valleys there was manifested a great dearth 



of knowledge. * W I am in doubt whether there is more than one valley 

 in Massachusetts that is, strictly speaking. : i valley of denudation," 

 that being the one lying between Mount Toby and Sugar Loaf. The 

 valleys in Berkshire and Worcester and possibly also that of the 

 Merrimac River were regarded as primary, more or less modified by 

 deluges and other abrading agencies. 



Accompanying this report was a volume of nineteen plates, com- 

 prising a colored geological map of the State; nine general and 

 special views; four of fossils; a map of the valley of the Connecticut: 

 a map showing the direction of the strata; two plates of sections, 

 three of which ran in an east and west direction and one in a north 

 and south; and one "tabular view" of the rocks and their imbedded 

 minerals. 



On the map the rocks were colored as belonging to six groups, as 

 below. It will be noted that there is no attempt at other than a litho- 

 logical classification until the New Red sandstone and Tertiary are 

 reached. 



II. Granite. 



2. Syenite. 



3. Greenstone. 



4. Porphyry. 



15. Gneiss. 



6. Hornblende slate associated with gneiss. 



7. Quartz rocks associated with gneiss. 



8. Mica slate. 



9. Quartz rock. 



10. Talcose slate. 



11. Chlorite slate. 



12. Hornblende slate. 



13. Limestone. 



14. Seapolite rock. 



, T . „ (Steatite. 



Miscellaneous lc ,. 



| serpentine. 



115. Grauwacke. 



16. Argillaceous slate. 



17. New Red sandstone. 



(18. Tertiary. 



6 19. Diluvium. 



120. Alluvium. 



Deposits and mines of useful minerals were noted, among them 

 being plumbago, coal, peat, lead, iron, copper, and manganese. 



The drawings of fossils and the general views were the work of 

 Mrs. Hitchcock. 



In 1837 Doctor Hitchcock was commissioned by Governor Everett 

 to make a further geological and mineralogical survey in which 



