50 BULLETIN 109, LT^ITED STATES :NATI{)NAL MUSEUM. 



another are successively to the e;ist of one another, or to the west, en echeUMi 

 (as the French style it) ; and, further, that the parts of the component ridges of 

 a range were often curved, or a succession of curving lines. He discovered, too, 

 that in the region of the Jleriden Hanging Hills the trap ridges take a singular 

 east and west bend across the great central valley of the State — a course 

 wholly at variance with the old notions. 



The work which he accomplished was, in the first place, an extended top<> 

 graphical survey of this portion of the State, and, secondly, a thorough exami- 

 nation of the structure and relations of the trap ridges, with also those of the 

 associated sandstone. And it brought out, as its grand result, a system of 

 general truths with regard to the fractures of the earth's crust, which, as 

 geologists are beginning to see, are the very same that are fundamental in the 

 constitution of mountain chains. For this combination of many appr-oximately 

 l)arallel lines of ranges in one system, the composite structure of the several 

 ranges and the en echelon, or advancing and retreating arrangement of the 

 successive ridges of a range, are common features of mountain chains. The 

 eartli's great mountains and the trap ranges of central New England are results 

 of subterranean forces acting upon the earth's crust according to common laws. 

 The State of Connecticut, tlirough the mind and labors of Percival, has con- 

 ti'ibuted the best and fullest exemplification of the laws yet obtained, and thus 

 prepared the way for a ccnrect understanding of the great features of the 

 globe. * '■' '■■ 



Percival pursued his second subject, that of the granitic rocks, with similar 

 fidelity, and mapped out with care the several formations. * * * His labors 

 were not without practical results, for he was the first to explain correctly the 

 origin of the iron-ore beds of Kent and similar beds in the Green Mountain 

 range.' 



The receipt of this report gave rise to the following resolution: 



At the general assembly of the State of Connecticut, holden at New Haven in 

 said State, on the first Wednesday of May, in the year of our Lord one thousand 

 eight hundred and forty-two. 



Resolved hy this asscmblij. Thai not less th:in 1,000 copies of Dr. .James G. 

 Percival's report on the geology of Connecticut be published under the sujmrin- 

 tendence of the author, and that a sum not exceeding $1,500 be appropriated to 

 defray the expenses of printing and superintending, and thnt the controller of 

 the public accounts be hei-eby authorized to draw an order on the treasurer for 

 such sum, not exceeding $1,500, to be paid out of money not otherwise appro- 

 priated; and his excellency the governor and Hon. Henry W. Edwards ai>- 

 hereby api)ointed commissioners to see the object of this resolution effected. 



And he it further resolved, That the commissioners before named be author- 

 ized to c-uise the copn-right of the said report to be secured to the State and to 

 jiermit any additional number of copies to be published and disposed of in such 



'Messrs. Gregory and Robinson, of tlie present survey (1907), in like manner render 

 appreciative testimony : " Perciral's Report on the Geology of Connecticut is not a read- 

 able book; it does not contain theories and inferences and bits of lively description, bui 

 merely dry facts grouped geographically. It is about the last book which a poet, one of 

 the most celebrated of his time, would be expected to write. Accuracy and keenness of 

 observation and distinctness of representation are, however, prime requisites for lasting 

 scientific work, and in these qualities Percival excelled. The more the modern geologist 

 becomes familiar with the involved structures and exasperating variations found within 

 the metamorphic rocks of the State, the more respect and admiration he has for Percival's 

 discrimination and skill of delineation. It is doubtful If ever a more accurate discrimina- 

 tion of the various members of a complicated series of crystalline rocks on field evidence 

 alone was ever accomplished." 



