No. 104. J 183 



In 1864, Prof. James Hall and Sir William Logan visited the dis- 

 trict and announced, as a result of their examinations, the existence of 

 Laurentian rocks in the Highlands.* 



In the same year Prof. George H. Cook, State Geologist of New 

 Jersey, mapped the Highlands (west of the Hudson and the Xew 

 Jersey range) as Azoic.\ 



The same district was represented, with much detail of geological 

 boundaries, on the map of northern New Jersey, which accompanied 

 the '•' Geology of New Jersey," published in 1868. The term Azoic 

 was retained.! 



Reference has already been made, to several articles by Prof. Jas. D. 

 Dana on the geological structure of the south-eastern part of the 

 State. § The term ArchcBan was proposed by him in 1872 for the 

 gneisses of the Highlands, in an article in the American Journal of 

 Science, on the " Poughquag Quartzite."|| In 1879, and in the same 

 journal he gave the boundaries, in part, of the Highlands Archasan 

 on a small (page) geological map of that part of the State. ^ In sub- 

 sequent articles on the "Geological relations of the Limestone Belts 

 of Westchester county," Prof. Dana assigns the crystalline rocks of the 

 Highlands to the Archa3an ; and in one of them he gives a map show- 

 ing these belts with the Archrean of Putnam county. ** References to 

 the rocks of Dover or East mountain, which have been described in 

 the preceding pages of Archrean and an outlier of the Highlands, are 

 made by the same author in a paper entitled '^ on Taconic Rocks and 

 Stratigraphy," published in March, 1885. ff 



The crystalline rocks of the Highlands of New York have been de- 

 scribed in tliis report as belonging to the Archcean Era. This term 

 has been accepted in preference to the older designation. Azoic, be- 

 cause it is not open to the objections which are foi'cibly opposed to the 

 use of the latter, when applied to these rocks. We cannot draw the 

 line where life began on the globe, but from the standpoint of a grad-* 

 ual development from lower to higher organisms it is reasonable to as-S 

 sume that the earliest life consisted of infusorial protophytes, which i 

 lived in conditions such as prevailed during the deposition of the first, 

 sediments. And they may have given rise to much of the carbon-' 

 aceoas and siliceous deposits so common in these crystalline gneisses, \^ 

 limestones and associated strata. A priori we should not look for the i 

 preservation of the earliest microscopic forms in beds M'hich have beenj 

 so metamorphosed as the older crystalline rocks. The presence of^ 

 limestone, graphite and apatite with beds of iron ore prove as much ^ 

 for the existence of life as the reverse. Again the term Azoic is/ 

 expressive of a negative condition aud not in harmony w'ith the other/ 'v^ 

 terms of the geological scale. It is not as consistent with Palceozoici X" 

 Mesozoic and Cenozoic as Archman, which refers to a period of geologi-? 



* Am. Jour, of Science (2), XXXIX, pp. 96-97. (Notice of a paper read oefore the Nat. 

 Hist. Soc. of Montreal.) 



•f- Am. Report of the State Geolorjixt^for 1864, map facing page 23. 



X Geology of New Jersey, 1868, Portfolio of maps ; Map of JSorthern Neic Jersey. 



§ See pages of this report. 



I Am. Jour, of Science {Z), III, pp. 253-254. 



IT Am,. Jour, 'of Science (3), XVII, p. 379 



**Am. Jour, of Science (3), XIX, p. 191 ; XX, pp. 21-22; and 368-375; XXII, pp. 105-lOS, 

 11 



i\Am. Jour, of Science (Z), XXIX, pp. 209, 221. 



