298 J. F. Kemp — Basic Dike near Hamburg, N. J. 



Art. XXXV.— A Basic Dike near Hamburg, Sussex Co., 

 New Jersey, which has been thought to contain Leu cite • by 

 J. F. Kemp. 



In June, 1888, the writer visited the exposures of basic 

 igneous rock, near the Beemerville, N. J., elseolite-syenite and. 

 on the materials collected, published a short description in this 

 Journal for August, 1889.* As stated in the paper, the avail- 

 able specimens were much decomposed, and yet as some plagio- 

 clase was noted they were called porphyrite. The presence of 

 nepheline was strongly suspected, but although unusually large 

 and abundant apatite appeared, no nepheline could be identi- 

 fied, owing doubtless to advanced alteration. 



In the two or three years since the paper was published, 

 there have appeared several descriptions of elseolite-syenite areas 

 elsewhere, and in particular of the basic rocks associated with 

 them ; so that we have come to recognize basic dikes as a quite 

 invariable attendant upon this form of plutonic rock. This 

 has proved true of the elseolite-syenite at Magnet Cove, Ark.f 

 Montreal, Canada,;}: and Salem, Mass.,§ in this country; of the 

 exposures in the Serra de Tingua, near Rio Janeiro, Brazil, | in 

 the Monchique Mountains of southern Portugal -*\ and near 

 Christiania, Norway.** The basic dikes are analogous to basal- 

 tic rocks of various types, including augitite, limburgite, meli- 

 lite-basalt, feldspar-basalt, and the like, but to preserve the 

 special grouping of dike rocks by themselves, they have re- 

 ceived individual names, fourchite, monchiquite, alnoite, etc. 



When this literature became available, it was at once seen 

 that the Beemerville dikes or bosses, (they appear more like 

 the latter in instances) were analogous to these, and in the 

 Arkansas Report, (Ann. Rep. 1890, vol. ii, p. 403), they were 

 stated to be practically the same thing as the Arkansas rocks 

 called ouachitite. 



In September, 1890, the writer went again to the Beemer- 

 ville syenite area,ff and was fortunate in learning through Mr. 



*On certain Porphyrite Bosses in Northwestern New Jersey, pp. 130-134. 



f J. F. Williams and J. F. Kemp, Second Ann. Rep. State Geologist of Ark., 

 vol. ii, pp. 290, 392. 



\ B. J. Harrington, Geol. Surv. Can. 1877-78, p. 429. F. D. Adams, this 

 Journal, April, 1892, p. 269. 



§ J. £. Wolff, Geol. Soc. Amer., hi, p. 84. 



|| O. A. Derby, Quart. Jour. Geol. Soc, xliii, 457, and xlvii, 251, (especially 265). 



TT Hunter and Rosenbusch, Tsch. Min. und Petr. Mirth., xi, 455, 1890. and 

 still earlier by L. Van Werveke, Neues Jahrbuch, 1879, p. 451, and 1880, pp. 

 141-186, but especially 179. 



** W. C. BrOgger, Zeitschrift f. Kryst , vol. xvi, 1890, p. 79. 



ff Eteolite-syenite near Beemerville, N. J., Trans. N. T. Acad. Sci., vol. xi, p. 

 60, Feb. 1892. 



