70 TRANSACTIONS OF THE [fEB. 1, 



spherulites like the kug-el minettes of the Germans. Mr. Derby, 

 however, at once remarked their likeness to altered leucite crystals 

 now being- studied by himself and Hus.sak in Brazil. I am not 

 prepared to speak authoritatively on them as yet. 



The dike is doubtless connected with the syenite eruption. It 

 contains a reddish biotite, the same yellow pyroxene mentioned in 

 the elaeolite porphyry, aegirine, titanite, feldspar, analcite second- 

 ary from nepheline, and nepheline. It is satisfactorily fresh. 



Emerson mentions a crystalline mass of calcite, biotite, and mag- 

 netite, from a point above D. B. Roloson's, which he regards as the 

 result of contact metamorphism. I have been to the same locality, 

 and have found the ouachitite further up the hill. So far as I know, 

 limestone is unknown in the shale of the vicinity, and I regard the 

 specimen in question as a thoroughly altered ouachitite. 



Contact Metamorphism. — The intrusion of this great body of 

 rock has naturally exerted a powerful influence on the neighboring 

 shales. Haeusser and Emerson remark this effect at the distance of 

 a mile to the east, and the same was noted bv myself. 



Eaierson describes a specimen from the north as resembling a 

 claystone porphyry. In a felsitic groundmass are opaque Carlsbad 

 twins of orthoclase, six to eight millimeters across, with chlorite, 

 small rhombs of calcite and cubes of pyrite. The groundmass with 

 high powers was resolved into line scales of muscovite. Some in- 

 cipient crystallizations suggested chiastolite crystals by the collec- 

 tion of colored hydrocarbons. 



My slides show a great development of biotite in the hornstone of 

 the contact, and this gives the dark color to the rock. The leaves 

 in the densest specimens are of extreme minuteness, sinking to 

 0.001 of a millimeter. In others they are coarser. They lie paral- 

 lel and suggest the foliation of a mica schist; but they give no evi- 

 dence of this to the macroscopic examination. Quartz is also present 

 and probably feldspathic matter. 



Along the Brick House Road, on the extreme south, one of the 

 best opportunities is afforded for the study of the contact effects 

 The baked flinty shales outcrop in the road in places and appear to 

 be seamed by narrow apophy.sae from the main dike. 



Slides of other shales gathered from |ioints apparently near the 

 dike show only a clastic mass of very fine grain, and as soon as 

 a distance of 200 to 300 yards is reached, or even less, unless a 

 ouachitite dike has been intruded, there seems to be no noticeable 

 mineralogical change, although the greater density and hardness 

 are very apparent. 



The ouachitites come out as eruptive breccia in part, and are not 

 to be confused with contact influences. Some slides of very fine 

 slate from near the contact with them show no mineralogical change, 

 and in general the metamorphism seems rather physical than mine- 

 ralogical. 



The contact influence on the Kittatinny sandstone and conglome- 

 rate is not discernible. The clastic character remains unaltered. 



