M PROCEEDINGS OF WASHINGTON MEETING. 



ville exposure and of the previous description by Professor B. K. Emerson. It is 

 shown that only the northern third of a dike three miles long had been treated. 

 Reference is also made to the associated basic rocks, already described by the 

 author, and they are stated to be identical with some peculiar dikes of which an 

 an ■Hunt by the author will appear in a forthcoming reporl of the Arkansas geologic 

 survey, where they are called ouachitite: 



The extent and geologic relations of the Beemerville syenite are next taken up 

 in detail. The syenite comes out as a great dike three miles in length, running 

 northeastward on the contact between the Kittatiny (Oneida) conglomerate and 

 the Hudson River (Trenton) slates. It is 300 to 400 yards wide. The dike was 

 followed from the northern to the southern end; the rocks collected are described 

 from thin sections and chemical analyses. As principal results.it is shown that 

 normal elseolite-syenite forms the northern third and the southern extremity ; that 

 most excellent ebeoi ite-por] ihy ry occurs in the middle third; and that toward the 

 southern extremity the dike becomes much more basic, running down to about 41 

 to 4*J per cent Si0 2 , and showing marked affinities with theralite. The normal 

 elseolite-syenite contains orthoclase, elseolite, cancrinite, sodalite, aegirine, reddish- 

 brown biotite, titanite. magnetite and pyrite. Fluorite has been detected by Pro- 

 fessor Rosenbusch in some specimens sent him, although overlooked by the writer. 

 Careful search failed to discover either eudialyte or eucolite. The elaeolite-porphyry 

 contains crystals of elseolite up to an inch in diameter. Almost at the same time 

 with its discovery, this type of rock was also found in Arkansas by the late J. 

 Francis Williams, with whom the writer was in active correspondence; and these 

 two are the firs! announcements of this rare species in the United States. The 

 rock resembles the Brazilian tinguaites, and has additional mineralogical peculiar- 

 ities to those mentioned above. The very basic rock of the south is worthy of com- 

 ment, and the remarkable absence of plagioclase from a rock so low in silica may 



he emphasized. 



A discussion of the associated basic rocks (ouachitites) follows, and some inter- 

 esting facts are brought out as to their relations with similar rocks elsewhere in 



'lie world. Some new dikes are also recorded. The paper closes with a short 



Lescription of the contact metamorphism. Acknowledgments are due to Dr. J. 



Francis Williams, of Cornell University (recently deceased .and to Professor H. 



Rosenbusch for valuable aid. 



In the subsequent discussion -I. Francis Williams announced that 

 \Y. S. Bayley, * > t ' Colby University, had discovered elaeolite in the horn- 

 blende-syenite of Hawes from New Hampshire; and J. E. Wolff stated 

 that he had learned of basic rocks occurring in close association with the 

 Salem, Massachusetts, elaeolite-syenite. Further remarks were made by 

 G. II. William.-, on the general subject of the paper, and by J. E. Wolff 

 on related rocks recently examined by him in the Crazy mountains of 

 Montana. 



