September 7, 1S83.] 



SCIEXCE. 



323 



connection were discussed. It was declared that the 

 views put fortli by the author in 1870-71, on the rela- 

 tions and succession of the crystalline stratified rooks 

 in Nortli America, and then extended by liim to 

 Europe, liave been fully confirmed by the labors of 

 a great many European geologists, as already shown. 

 Those of Ilicks, Hughes, Bonney, Callaway, Lap- 

 worth, and others, in the pre-Cambrian rocks of the 

 British islands, were cited in support of these con- 

 clusions. It was said, that, whatever may have 

 been the conditions under which these vast series of 

 crystalline stratified rocks were deposited, there is 

 evidence, in the similarity of their mineralogical and 

 geognostical relations, of a remarkable uniformity 

 over widely separated regions of the earth's surface, 

 as well as of long intervals of time, marked by great 

 foldings and disturbance, and by vast and wide-spread 

 erosion of the successive series of rocks. 



In conclusion, the writer took occasion to call 

 attention to the important labors of the present 

 school of Italian geologists, and their great zeal, skill, 

 and disinterested service, as shown in the memoirs 

 of the R. accaderaia dei lincei, and in ths work of 

 the Royal geological commission. Including the special 

 studies, maps, and memoirs prepared by it for the 

 International geological congress of Bologna in 1881. 

 The new Geological society of Italy, founded at the 

 same date, gives promise of a brilliant future, and 

 has already published m.iny important memoirs. 



The serpentine of Staten Island, New York. 



BY T. STEISRY HUNT OF MOXTKIiAL, CAN. 



Thk serpentine of Staten Island appears as a uorth- 

 and-south range of bold hills rising out of a plain of 

 inesozoic rocks, which on the west side are triassic 

 sandstones like those of the adjacent mainland, in- 

 cluding a belt of intrusive diorite, and on the east the 

 overlying, nearly horizontal, cretaceous marls, which 

 are traced south and west into New Jersey. The only 

 rocks besides these mentioned, seen on the island, are 

 small areas of a coarse-grained granite, having tin- 

 character of a veinstone or endogenous mass, and 

 others of an actinolite rock; both exposed among 

 the sands on the north-east shore of the island. 



Mather, who described this locality more than forty 

 years since, looked upon the serpentine as an eruptive 

 rock, related in origin to the parallel belt of diabase 

 which is included in the triassic sandstone to the west. 

 Dr. Brilton, of the School of mines, Columbia college, 

 who in ISSO publisbed, in the transactions of the New- 

 York academy of sciences, a careful geological de- 

 scription and map of the island, regarded the serpeft- 

 tine belt as a protruding portion of the eozoic series, 

 including serpentine, which is seen at Hoboken, on 

 Manhattan Island, and in Westchester County, New 

 York, — a conclusion which the writer reganis as un- 

 questionably correct. 



The appearance of isolated hills and ridges of ser- 

 pentine is common in other regions, and is by the 

 writer explained by the consideration that this very 

 insoluble magnesian silicate resists the atmuspheric 

 agencies which dissolve limestones, and convert 



gneisses to clay; the removal of which rocks leaves 

 exposed the included beds and lenticular masses of 

 serpentine. Similar appearances are seen in many 

 parts of Italy, where ridges and bosses of serpentine 

 are found protruding in the midst of eocene strata, 

 and have hitherto by most European geologists been 

 regarded as eruptive masses of tertiary age. The 

 jiroblem is there often complicated by the fact that 

 subsequent raovemcnis of the earth's crust have in- 

 volved alike the older crystalline strata (of which the 

 serpentines form an integral part) .ind the uiicoii- 

 formably overlying eocene beds; faulting and folding 

 the latter, and even giving rise to inversions by which 

 the newer rocks, overturned, are made to dip towards 

 and beneath the ancient crystalline masses. This 

 the writer illustrated by reference to localities re- 

 cently examined by him in Liguria and in Tuscany, 

 where this rel.ation of the serpentines had already 

 been pointed out by Gastaldi. The structure in 

 question was declared to be analogous to that pre- 

 sented by similar foldings and overturns to be seen 

 along the western base of the Atlantic belt through- 

 out the Appalachian valley. 



Tlie speaker further alluded to the fact, that, al- 

 though the sub-aerial decay of serpentine was far less 

 rapid than that of most other rocks, it had not escaped 

 this process; and described the decayed layer on por- 

 tions of the Staten Island serpentine hills, including 

 a chromiferous limonite segregated from the decayed 

 serpentine. This was a slow pre-glacial process, and 

 in the subsequent erosion of the serpentine ridges 

 the decayed layer has been in parts entirely removed. 

 The details of this decay, and its rel.ations to the 

 limonite, and to glaciation in this locality, have 

 been described by the writer in an essay on the de- 

 cay of rocks, to appear in the American journal of 

 science for September, 18sj. lie gratefully acknowl- 

 edged his personal obligations to Dr. Britten for the 

 many facts contained in his memoir and map, as well 

 as for personal guidance during a late visit to Stateu 

 Island. 



The equivalent of the New- York water-lime 

 group developed iu Iowa. 



BY A. S. TllrANY Of DAVENPdKT, 10. 



TnE author stated, that the upper Silurian rocks 

 of Iowa had hitherto been classed wholly as of the 

 Niagara limestone. There has, however, been some 

 dispute as to the magnesian buff-colored limestone 

 of the Le Claire and Anamosa quarries. Such dis- 

 putes must, of course, be settled by the fossils; but 

 he had been for more than twelve years seeking 

 organic remains in that formation, without success 

 until February of last year, when he found them in 

 considerable quantities. ,Si)ecimens of. the fossils 

 were exhibited. Mr. Tiffany considered that they 

 gave conclusive evidence of belonging to a group 

 higher in the scale than the fossils of the Niagara 

 limestone, that their affinities were with those of 

 the water-lime group of the lower llelderberg, and 

 that the identity nf many species had been deter- 

 mined. 



