SOSMAN AND MERWIN: DATA ON PALISADE DIABASE 389 



GEOPHYSICS. Data on the intrusion temperature of the pali- 

 sade diabase. R. B. Sosman and H. E. Merwin, Geophysi- 

 cal Laboratory. 



In his report on the petrography of the Newark igneous rocks 

 of New Jersey,^ Prof. J. Volney Lewis has described an interest- 

 ing type of inclusion which occurs frequently in the Palisade dia- 

 base. Slabs of the underlying Newark shale and arkose sand- 

 stone have been "floated" up into the igneous rock until they 

 stand at various angles between horizontal and vertical. In con- 

 nection with an investigation on the specific volumes of rocks at 

 high temperatures it became of interest to compare the specific vol- 

 umes of the included and including rocks in this type of inclusion. 

 Professor Lewis very kindly supplied us with specimens for 

 the purpose, and our indebtedness to him both for material and 

 for published descriptions is here acknowledged. 



The specimens first obtained were from the quarry of the Fair- 

 view Stone Crushing Company, at the north end of the diabase 

 hill between Fairview and Granton, New Jersey. This mass is 

 an offshoot of the great Palisade sill which outcrops along the 

 west bank of the Hudson River and extends southwest thru New 

 Jersey. It lies only 800 feet west of the western border of the 

 main sill, and is not over 200 feet vertically above the upper 

 surface of this silL- 



In 1907 there was visible in the quarry mentioned ''an arkosic 

 sandstone slab about 10 feet thick at one end and tapering to 

 about 5 feet at the other and over 100 feet long, lying at an angle 

 of about 10 degrees with the horizon. This inclusion is within 

 10 feet of the bottom of the diabase sheet, which here rests on 

 thinly laminated black and gray shales." We are informed by 

 Professor Lewis that since that time quarrying operations have 

 followed this slab back until it joined the underlying strata, 

 thus establishing its connection with the floor of the intrusive 

 mass. It was, therefore, not possible to obtain specimens of the 

 actual inclusion, but specimens of the underlying arkosic sand- 



^Geol. Surv. New Jersey, Ann. Rep., 1907, pp. 97-167. See, in particular, 

 pis. 27 and 28, and p. 135. 



2 J. V. Lewis, Geol. Surv. New Jersey, Ann. Rep., 1906, p. 122; H. B. Kuem- 

 mel, ibid., 1897, p. 73. 



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