1892.] NEW YORK ACADEMY OF SCIENCES. 61 



by J. p. Kimball,^ and a zircon syenite (so-called) is mentioned by 

 Wadsworth from Marbleliead, Massachusetts.^ 



The Arkansas areas have long- been known as a prolific source of 

 many rare and intei'esting minerals, and in connection with these 

 and in the old ^-eological reports of the State some mention of the 

 rocks is made; but only the recent report of the late Dr. J. Francis 

 Williams treats the matter with thoroughness. Although usually 

 colored as Archaean on the geological maps in the past, they are 

 now known to be late Cretaceous. 



The Beemerville area was first noted by E. Haeusser, an assistant 

 on the New Jersey survey under Dr. Kitchell, and from his notes a 

 brief description is taken for the New Jersey Report for 1868, p. 

 144. The notes are valuable as announcing the existence of the 

 great dike, but subsequent investigation has shown that the chief 

 minerals (hypersthene and labradorite) mentioned by Haeusser are 

 entirelv lacking. The true nature of the rock was thus overlooked 

 b}^ him. The remarks, however, were fruitful in bringing it to the 

 attention of Prof. B. K. Emerson,* who visited it in 1881 and 

 recognized the true character of the portion traversed by him. 

 Prof. f]merson seems, however, to have touched the dike at only 

 one or two points at the northern end ; and as it extends nearly 

 three miles in a northeast and southwest direction, much the greater 

 part has remained to be sul)jected to the microscope. 



Several outcrops of a curious basic rock occur east of the syenite, 

 which were mentioned in the New Jersey Report for 1882, p. 67. 

 These were subsequently more fully investigated by myself* and 

 called porphyrite. Investigations and papers which have since ap- 

 peared have much enlarged our knowledge of the basic rocks associ- 

 ated with elaeolite syenites in other localities, and the true relations 

 of these so-called porphyrites are with the extreme basic non-feld- 

 spathic end of the lamprophyre division. 



Rosenbusch has created the name monchiquite as applied to those 

 with much olivine from Brazil, and J. Francis Williams has called 

 others from Arkan.sas,with no olivine but with prevailing augite, four- 

 chite ; and I have named still another variety from Arkansas, with 

 great amounts of biotite, ouachitite. The Beemerville basic rocks are 

 ouachitite. 



The elaeolite-syenite dike lies on the southeastern slope of the 

 Kittatinny Mountain ridge, and some eight miles west of Decker- 

 town, the nearest railway station. Deckertown is situated at the 

 crossing of the New York, Susquehanna and Western, by the Penn- 



1 J. P. Kimball, On Sodalite and Elaf»olite from Salem, Mass., A. J. S., ii, 

 xxix. 6.5, quotes Gr. L. Streeter, in Prnc. Essex Inst., ii, 153. 



2 Zircon syenite from MarMehead, Mass., Proc. B. S. N. H., xxi. 40(), 1880-82. 



3 B. K. Emerson, On a Great Dike of Foyaite or Elaeolite Syenite in North- 

 western New .Jersey, A. .1. S., iii, xxiii, 302. A fall quotation of Haeusser's 

 notes is made in the paper. 



* J. F. Kemp, On Certain Porphyrite Bosses in Northwestern New Jersey, 

 A. J. S., iii, xxxviii, 130. 



