22 TRANSACTIONS OF THE [OCT. 24,. 



determinations by Dr. A. A. Julian. The rocks (except the dia- 

 base) are shown to contain j^lagioclase (largely anorthite), hyper- 

 sthene, hornblende, diallage, magnetite, menaccanite, and gar- 

 net. They are both massive and gneissoid. Dr. Leeds gives six 

 conclusions. I. The rocks of Essex Co. are parts of the Norian 

 system and are composed of norites like those in Canada, 

 V/estern Scotland, Norway and elsewhere. II. That they are a 

 stratified rock, which has undergone a metamorphism so profound 

 as to cause them to be regarded by Emmons and others as 

 massive. That the dolerites have come from another portion of 

 lower lying, stratified rocks and have tilted the norites in their 

 extrusion. III. The norites are marked by a paucity of silica 

 due to the presence of bisilicates and to anorthite among the 

 plagioclases. IV. The alkalies are deficient. V. Menaccanite 

 is universal in both labradorite and pj-roxenes VI. The men- 

 accanite contains chromium. The additions made b}' thisjoaper 

 to our knowledge of the chemical composition of these rocks 

 are most praiseworthy, but the conclusions under II. are 

 warranted by no commensurate field-work as evinced by the 

 paper, and, remembering the mineralogy of the rocks, they 

 would be considered in the estimation of petrographers as 

 untenable. (See also A. R. C. Selwyn, Rep. Prog. Can. Sur., 

 1877-78.) 



In 1879 C. E. Hall published a paper on the " Laurentian 

 Magnetic Iron Ore Deposits in Northern N. Y.'' (32nd Annual 

 Report of the N. Y. State Cabinet, 1879, pp. 133-140.) The 

 geology of the eastern Adirondacks is dirscussed very briefly by 

 townships. The Archaean rocks are divided into : I. Lower 

 Laurentian Magnetic Iron Ore Series. II. Laurentian Sulphur 

 Ore Series. III. The Crystallina Limestones. IV. Labrador 

 Series or Upper Laurentian with titaniferous ores. The 

 relations of II. and III. are said to be uncertain, but later in a 

 note the limestone of III. is stated to be later than IV. A 

 geological maj) accompanies the report. 



G. P. Merrill, of the U. S. National Museum, has given 

 attention to the serpeutinous limestones as having somebesiring 

 on the Eozoon Canadense. This problematic association of 

 serpentine and calcite had been previously announced from 

 "Warren Co. by A. M. Edwards. (Lyceum of Natural History, 

 N. Y., Proc, 1870, p. 96.) Two papers have come from Mr. 

 Merrill, the one on the " Ophiolite of Thurman, Warren Co., '^ 

 etc., Amer. Jour, of Sci., ^Far., 1889; and the other, "On 

 Serpeutinous Rocks from Essex Co., N. Y. etc.," Proc. U. S. 

 National Museum, XII., 595, 1890. The serpentine appears to 

 be both an alteration product from a white pyroxene, cores of 



