ACGITE OF THE "GREENSTONE OPHITE 



371 



certain that the initial temperature was but little above that of consoli- 

 dation. We do not know the gradient close to the margin, and that is 

 the point, anyway, where the convection currents and the earlier crystal- 

 lization that takes place produces the most irregularities. 



For these high values ofuluo, h changes quite rapidly, and hence we 

 can not determine K with any exactness unless we had C, which is not 

 the case. 



Palisade Trap 



The great intrusive sheet of the palisades of the Hudson is well known 

 to most American geologists. It has been described by Darton, Kiimmell, 

 Andrese and Osann, and Queneau, besides earlier writers whose works 

 are noted by Darton and Kiimmell.* 



If we take the observations on grain for this trap sheet, which consists 

 essentially of an aggregate of augite and labradorite with occasional acid 

 interstices containing micropegmatite with small amounts of brown mica 

 and opaque iron ore and a certain amount of h3^persthene, we find that 

 all writers refer to a marginal zone in which the grain decreases. The 

 whole thickness, according to Kiimmell, is about 300 meters. 



If we take one set of Queneau's results for augite given on page 192 

 and find the linear dimensions, we may construct the following table: 



Distance x^ in 

 millimeters. 



Difference. 



Linear grain in 

 millimeters. 



Difference. 



Ratio of differ- 

 ences. 





390 





.0824 



.000209 



390 





.0824 









1110 





—.0132 



• —.000012 



1500 





.0692 









2410 





.1283 



.0000532 



3910 





.1975 









3780 





.1855 



.0000491 



7690 





.3830 









3900 





.1660 



.0000426 



11590 





.5490 









5810 





.3070 



.0000528 



17400 





.8560 









5810 





.233 



.0000399 



23210 





1.089 









11280 





.068 



.000006 



34490 





1.141 







*The relations of the traps of the Newark system in the New Jersey region. Bull. No. 67, U. S. 

 Geol. Survey, 1890. See al.«o Size of grain of igneous roclis in relation to the distance from the 

 cooling wall, by Augustin L. Queneau, School of Mines Quarterlj^ xxiii, 181-19.5, January, 1902. 

 Contributions from the Geological Department of Columbia University. Amer. Jour. Science, 

 November, 1902, vol. xiv, page 393. Tiefencontacte an den intrusiven Diabasen von New-Jersey, 

 Von Andrese und A. Osann. Separat-Abdruck aus den Verhandlungen des Naturhist.-Med. Vereins 

 zu Heidelberg. N. F. V. Bd. 1, Heft. 



