AMERICAN GEOLOGY DECADE OF 1830-1839. 315 



The idea was, however, brought out much more clearly in a com- 

 munication made by him before the Association of American Geol- 

 ogists and Naturalists in 1841, an abstract of which was given in their 

 Proceedings and in the American Journal of Science for the same 

 year. He then called attention to the "inverted dip' 1 observable 

 among the rocks of the Coal Measures (of Pennsylvania) and ascribed 

 the same to a great force acting laterally, folding and crushing the axis 

 so as to produce this inverted dip by tossing the strata many degrees 

 beyond the perpendicular, thus producing the present apparent dip of 

 the lower stratified or sedimentary rocks beneath the primary. 



In view of the observations made by Eaton in 1820, Steel, in 1825, 

 and W. B. Rogers, in Virginia, in 1838, as noted elsewhere, the sub- 

 ject of priority between the two first named is scarcely worth discussing. 



Heavy demands have from a very early time been made upon elec- 

 tric currents to account for all sorts of geological phenomena, from 

 the formation of ore deposits to the production of slaty cleavage, or 

 even the uplifting of mountain ranges. It is not strange, therefore, 

 that Doctor Hitchcock should have felt justified in making slight 

 draft upon it to help him over some of his minor difficulties. The 

 peculiar imitative and otherwise interesting forms assumed by the 

 ferruginous concretions found in the Connecticut Valley demanded an 

 explanation. "I know of no agent," he wrote, . u that could have 

 accomplished this (i. e., the separation of the iron from the menstruum 

 which held it in solution) except galvanic electricity," and again, "I 

 strongly suspect galvanism to have been a chief agent in concretions 

 of every sort/ 1 



In the report of 1833, and again in those of 1835 and 1841, Hitch- 

 cock called attention to the peculiarly flattened and otherwise distorted 

 pebbles in the conglomerate at what is locally known as Purgatory, 

 near Newport, Rhode Island. His description is important in view of 

 his subsequent writings and the discussions which arose in connection 

 therewith. The subject may, however, well go over until his later 

 paper of 1861 (see p. 510). 



This final report, coming at the time it did, naturally attracted much 

 attention and favorable comment. From a brief preliminary review in 

 the American Journal of Science the following paragraph is selected: 



If we reflect that the vast mass of facts and information of various descriptions, 

 and the reasonings and inferences contained in these columns, are all the result of 

 untiring, nay, almost Herculean, efforts of an individual mind, continued among the 

 harassments of constant professional duty during a period of ten years, we are 

 encouraged to hope that we may yet see the day when the united efforts of our small 

 army of working geologists now laboring in the common cause shall reduce the whole 

 of our widespread territory to an intelligible perfect system. 



Although our sketches have thus far been confined largely to 

 xVmericans, either by birth or adoption, the times with which we are 



