8 SMITHSONIAN MISCELLANEOUS COLLECTIONS \'0L. 76 



of which is exhibited in the main hall of the Smithsonian Institution 

 building. Three of the photographs of wild flowers as growing are 

 reproduced by figures 8, 9, and 10. 



During most of the field season the party consisted of Secretary 

 and Mrs Walcott, Dr. Edwin Kirk of the U. S. Geological Survey, 

 Arthur Brown, Paul J. Stevens, packer, and William Harrison, camp 

 assistant. 



The Commissioner of the Canadian National Parks, Hon. ]. B. 

 Harkin, and the members of the Parks Service in the field, and the 

 officials and employees of the Canadian Pacific Railway, w^ere all 

 most courteous and helpful. 



GEOLOGICAL FIELD-WORK IN THE OHIO VALLEY 



The field-work for 1923 of Dr. R. S. Bassler, curator of paleon- 

 tology, United States National Museum, was limited to three regions 

 of the Ohio Valley, namely, the Central Basin of Tennessee, the 

 Knobstone area of southern Kentucky and the Niagaran plain of 

 southwestern Ohio. The stratigraphic and paleontologic studies in 

 the Central Basin of Tennessee, commenced two summers ago, were 

 continued this year in cooperation with the Geological Survey of Ten- 

 nessee. In previous field-work the geology of the western side of 

 the Central Basin, particularly an area of about 250 square miles just 

 south of Nashville, was studied and mapped. This season's work was 

 concentrated upon the Hollow Springs quadrangle, an area of similar 

 size located on the opposite side of the Central Basin and upon the 

 adjacent Highland Rim. This Highland Rim, a plain area underlaid 

 by very gently undulating strata, is a possible source of oil, so that 

 State Geologist Wilbur A. Nelson suggested that in addition to the 

 usual stratigraphic studies, a structural contour map be made oi the 

 quadrangle for use in locating oil areas. Therefore during the geologic 

 mapping special attention was paid to the accurate determination of 

 the top of the Chattanooga black shale, a widespread oil shale forma- 

 tion separating the Mississippian limestones above from the Ordovi- 

 cian limestone below. Sufficient observations were obtained to make 

 it possil)le to draw on the map the structural contours or lines of 

 equal elevation of the oil shale, thereby revealing the slight undula- 

 tions of the strata. Several anticlines of interest as possible oil reser- 

 voirs were discovered by this method. The stratigraphic sequence in 

 this region proved to be quite different from the western side of the 

 Central Basin for here the middle Ordovician. Cannon limestone as 

 shown in figure 12 is overlaid directly by the early Mississippian Chat- 



