"pele's tears" . 55 



Conclusion 



The forms of some of "Pele's tears" are so similar to the dumb-bell types of 

 australites as to demonstrate the probability of the latter being of volcanic 

 origin. These bodies of distinctly volcanic origin demonstrate the possibility 

 of bodies with such shapes as spheres, dumb-bells, etcetera, being formed in 

 the atmosphere from a rotating liquid body. There is no evidence in the com- 

 position of the lava that a specially viscous type of liquid is necessary to de- 

 velop these forms; but the magnesia and lime contents are high, and it appears 

 that we must look for some specially favorable condition of temperature, 

 pressure, or other physical circumstance to account for their origin, since they 

 are not, so far as known to the writer, common products of volcanoes. Thus 

 may some special condition also have given rise to the australites. 



No attempt is made here to throw fresh light on the distribution of the 

 australites in Australia, although it is the opinion of the writer that they are 

 of volcanic origin and the method of transportation will be discovered as the 

 geology of Australia becomes better known. 



TRIASSIG IGNEOUS BOOKS IN THE VICINITY OF GETTYSBURG, PENNSYLVANIA 

 BY GEORGE W. STOSE AND J. VOLNEY LEWIS 



(Abstract) 



CONTENTS 



Page 



Distribution and mode of occurrence 55 



Petrography 56 



General character 56 



Texture 56 



Order of crystallization ' 56 



Varieties of diabase 56 



Distribution and Mode of Occurrence (by g. w. stose) 



The igneous rocks are all intrusive. No basalt flows. One main sill crosses 

 the area from southwest to northeast just east of Gettysburg. Average thick- 

 ness, 2,500 feet. Dips under shales on west at 20°. Irregular outline in places 

 may be clue in part to cross-faulting. Average width of outcrop about 1 mile. 

 Local widening to over 2 miles, probably due to local thickening and corre- 

 sponding displacement of overlying shale. 



Two main cross-cutting bodies nearly at right angles to bedding. Larger 

 one, 1 mile thick. Offshoots from these form minor sills and cross-cutting 

 bodies. 



A sill along the plane of the flat, overlapping western contact of Triassic 

 sediments on Paleozoic limestone exposed at many places. 



Thin dikes and sills are in part later than the large sill and cross-cutting 

 bodies. 



The igneous magma seems to have entered the Triassic rocks near their 

 western border ; to have spread along the flat, western contact as a sill ; to 

 have extended laterally in a thick sheet between the layers as the Gettysburg 

 sill ; to have broken across the bedding in several places between these two 

 sills as cross-cutting bodies. Judging from the coarseness and thickness of the 



