No. 8.] BIBLIOGRAPHY OF CONNECTICUT GEOLOGY. 55 



the igneous origin of the traps is stated, and the fact of transportation 

 of bowlders and the direction of their course is noted. The author 

 described what he saw, and the book is a mass of geological detail. 

 With this abundance of facts, however, there is an absence of general- 

 izations or of an attempt to interpret the phenomena observed, and the 

 report is therefore of little value to the reader who wishes to under- 

 stand the geological history of Connecticut. — Ed.) 



230. Percival, James Gates, (i 795-1856.) 



Biography. 



Shepard: Atlantic Mon., iv, 59-73, 1859. 



Ward: Life and Letters of James Gates Percival. 579 

 pp., 1866. 



Pettee : Meriden Sci. Assoc, Trans., iv, 22-28, 1890. 



Cogswell : Percival and his friends. Am. Jour. Sci., (2) 

 xxii, ISO-I5I, 1856. 



Geol. Surv. Wisconsin, preface, 1856. 



231. Perry, J. B. 



Hints toward the post-Tertiary history of New England 

 from personal study of rocks, with strictures on Dana's " Geol- 

 ogy of the New Haven region." 



Boston Soc. Nat. Hist., Proc, xv, 48-148, 1873. 



Discussion of the non-adaptability of the iceberg theory to .ac- 

 count for all the drift phenomena. Detailed treatment of the glacier 

 theory and its general application to the post-Tertiary history of New 

 England. Discussion of the marl and peat periods of post-Pliocene 

 time. Criticism from time to time of Prof. Dana's article, " Geology of 

 the New Haven Region." 



232. Petros (C. A. Lee). 



The moving rocks of Salisbury. 



Am. Jour. Sci., (i) v, 34-36, map, 1822. 



Northeast pond and Little pond, now separated by a narrow strip of 

 limestone bowlders, were formerly one water body. Carrying of rocks 

 shoreward by the ice has built this barrier. Between September, 18:9, 

 and February, 1821, a rock weighing forty tons was moved shoreward 

 3 rods, 2 links, leaving a trench behind. 



(This is one of the first quantitative statements of the importance 

 of lake ice in transporting material. — -Ed.) 



233. Pierce, J. 



Chalybeate spring at Litchfield. 



Am. Jour. Sci., (i) iii, 235, 236, 1821. 



An account of a " copious and perennial spring issuing from an ex- 

 tensive bed of sulphuret of iron," situated on the eastern side of Mount 

 Prospect; exhibits in its course much oxide of iron, ochre, and a 

 white deposit. 



234. Porter, T. D. 



Floetz trap formation in Connecticut and Massachu- 

 setts. 



Am. Jour. Sci., (i) iv., 241-242, 1822. 



