104 HISTORICAL SKETCH

In July, 1892, Mr. C. D. Walcott, the present director, made an
examination of the Blue Ridge and South Mountain region and
definitely determined the Cambrian age of its quartzites. A state-
ment of the results of this investigation was set forth in two papers,
one entitled " Notes on the Cambrian Rocks of Pennsylvania and
Maryland from the Susquehanna to the Potomac, "¹ and the other
" The Geologist at Blue Mountain, Maryland. " ²

In 1892 Mr. Keith, having continued his studies of South Mountain
and Blue Ridge geology into Virginia, prepared a report on the " Ge-
ology of the Catoctin Belt. " This report describes the Blue Ridge,
South Mountain and Catoctin belts from northern Virginia through
Maryland into Pennsylvania. It treats of the character of the rocks
and their alteration, the general geologic relations and structures,
and reviews the geomorphic development of the region. ³

In the coal fields of western Maryland two investigations were made.
In 1886 Prof. I. C. White made an examination of the coal fields of
West Virginia, in which incidentally some study was made of the
coal basins of Western Maryland. The results of these and some
later observations by Professor White were published by the survey
in a report entitled " Stratigraphy of the Bituminous Coal Field in
Pennsylvania, Ohio and West Virginia. " ⁴

In the autumn of 1894 a party was organized under the direction
of Mr. Bailey Willis for the mapping of the Piedmont quadrangle,
which covers the southern part of Garrett county, Maryland. The
geologic work was done by Messrs. N. H. Darton and J. A. Taff. The
product is the Piedmont folio, No. 28, Geologic Atlas of the United
States, which was published in 1896.

Coastal Plain.

In July, 1883, the Potomac Division of Geology was organized, in
charge of W J McGee, for the purpose of studying the Coastal Plain

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. 14, 753-
14, 754.

³ Fourteenth Ann. Rept. U. S. Geol. Survey, part ii, 1894, pp. 285-395, pls.
xix-xxxix.

⁴ Bull. U. S. Geol. Survey No. 65, 1891, 212 pages, plates and maps.