158 J. V.Lewis — Palisade Diabase of J$ew Jersey. 



Analyses of Palisade Diabase. 





I 



II 



III 



SiO, 



... 60-05 



56-78 



51-34 



A1 2 3 ~~ 



... 11-88 



14-33 



12-71 



Fe 2 3 .___ 



3 -22 



5-76 



2-65 



FeO 



... 10-21 • 



9-27 



14-14 



MgO 



... 0-85 



1-58 



3-66 



CaO 



... 4-76 



5-26 



7-44 



Na 2 .... 



... 4-04 



3-43 



2-43 



K 2 ..... 



_ . 2-10 



1-75 



1-44 



H 2 0+ ... 



... 0-66 



o-io 



0-69 



H 2 0- ... 



... 0-21 



0-33 



0-18 



Ti0 2 



_.- 1-74 



1-44 



3-4-7 



P 2 5 ._... 



... 0-52 



0-36 



0-20 



MnO 



... 0-28 



0-25 



0-36 



IV 



49-02 



10-14 



1-54 



10-46 



17-25 



8-29 



1-59 



0-40 



0-59 



0-16 



0-99 



o-ii 



0-16 



i nrV7n 



100-52 100-04 100-71 



I. Pennsylvania R. R. tunnel, Homestead, 400 feet from the 

 west end. 



II. Old quarry near R. R. station, Rocky Hill, 420 feet from 

 upper surface of the trap. 



III. Pennslyvania R. R. cut 420 feet east of Marion station 

 (Tonnele Ave. ), Jersey City. 



IV. Englewood Cliffs, on the Palisades, 11 miles north of Jer- 

 sey City. From the olivine diabase ledge. 



I, III, and IV by R. B. Gage, chemist of the Geological Survey 

 of New Jersey ; II by A. H. Phillips of Princeton University 

 (this Journal, vol. viii, 1899, p. 267). 



In general, alumina, ferric iron, and the alkalis vary with 

 the silica, while ferrous iron, lime, and magnesia vary inversely. 

 Chemically these rocks overlap the andesite-diorite series on 

 the one hand and the most basic olivine-gabbros on the other, 

 and the extremes are characterized by abundant quartz and 

 olivine, respectively. 



Classification. — In the older terminology the prominent 

 facies of the Palisade sill would be known as quartz-diabase, 

 diabase, and olivine-diabase, the prefixes quartz and olivine 

 denoting special richness in these minerals. As indicated 

 above, most of the coarse-grained rock, which constitutes by 

 far the greater bulk of the Palisade sill from the Hudson to 

 the Delaware, is decidedly quartzose, this mineral being quite 

 generally present in graphic intergrowth with orthoclase. In 

 the most acid facies micropegmatite constitutes about one-third 

 of the bulk of the rock, but the average is probably somewhat 

 less than one-tenth. On the other hand, the most basic facies 

 contain 15 to 20 per cent of olivine, but this is confined to the 

 relatively small mass of the olivine-diabase ledge. Normal 

 diabase, without quartz or olivine, is much less abundant than 



