34 THE CAMBRIAN AND ORDOVICIAN DEPOSITS OF MARYLAND 



was set forth in two papers, one entitled " Notes on the Cambrian Bocks 

 of Pennsylvania and Maryland from the Susquehanna to the Potomac," * 

 and the other " The Geologist at Blue Mountain, Maryland." 2 



Mr. Keith continued his studies of South Mountain and Blue Kidgc 

 geology into Virginia and in 1894 published a report on the " Geology 

 of the Catoctin Belt."' This report describes the Blue Eidge, South 

 Mountain, and Catoctin belts -from northern Virginia through Maryland 

 into Pennsylvania and was an important addition to the geologic knowl- 

 edge of this area east of the Great Valley. 



The discovery of fossils in the Frederick Valley limestone was an- 

 nounced by Charles R. Keyes in 1890 4 in an article in which he included 

 a geologic section across the valley. The next contribution in which fossils 

 were mentioned was by Charles S. Prosser in 1900, 5 who described the 

 Shenandoah limestone and Martinsburg shale in a general way. 



The most important contributions to the early Paleozoic stratigraphy 

 of this region appeared in 1910 in the description of the Mercersburg-- 

 Chambersburg district of Pennsylvania by George W. Stose 8 in which 

 E. 0. Ulrich collaborated in the study of the Shenandoah limestone and 

 Martinsburg shale. Further stratigraphic and paleontologic details of 

 these rocks were given by E. 0. Ulrich in his " Revision of the Paleozoic 

 System " in 19.11/ 



BIBLIOGRAPHY 



1788 



JEFFERSON, THOMAS. Notes on the State of Virginia. Phila., 1788. 

 Sm. 8vo. 244 pp. 



The author gives many interesting facts and speculations concerning the geology 

 about Harper's Ferry. Fully ten editions of this book were published in different 

 places between 1782 and 1832, each with different number of pages. 



1 Amer. Jour. Sci., 3d series, vol. xliv, pp. 469-482. 



2 Nat. Geog. Mag., vol. v, pp. 84-88; Sci. Am. Supp., vol. xxxvii, pp. 14753-14754. 



3 Fourteenth Ann. Rep. U. S. Geol. Surv., part ii, 1894, pp. 285-395, pis. xix- 

 xxxix. 



4 Johns Hopkins University Circular No. 84, vol. x, 1890, p. 32. 



5 Journal Geology, vol. viii, pp. 655-663, figs. 1-4. 

 8 U. S. Geol. Survey, Geol. Atlas No. 170, 1910. 



1 Bull. Geol. Soc. America, vol. xxii, No. 3, pp. 281-680, 5 pis., 1911. 



