60 Correspondence. 
escape of waters southward around the edge of the ice. Between a few 
miles south of the mouth of White river and the mouth of the Niobrara, 
I have found no trace of drift more than three or four miles west of the 
Missouri, although I have examined at four separate points. A prominent 
reason for this close correspondence between the river and the edge of i he 
drift is found further in the fact that a high table land, more or less capped 
with this same "green quartzite," abuts upon the river through most of 
this distance. Above the White river and below the mouth of the Nio- 
brara, the limits of the drift leaves the immediate vicinity of the Missouri, 
as the adjoining land becomes less elevated. The bearing of this on the 
origin of the drift in those regions is significant. 
The first point where I met with this "green quartzite" was upon the top 
of the Bijou hills, where it forms a capping 12 to 15 feet in thickness. West 
of the Missouri it caps similar buttes, including the conspicuous Medicine 
butte, and 40 feet below the upper stratum there is another thinner but 
similar. The rock is fine grained sand sometimes obliquely stratified, 
irregularly thin-bedded, solidified for the most part into very compact 
vitreous stone. It often contains worn pebbles some of them resembling^ 
pitch-stone. By weathering it becomes whiter, and then resembles 
mortar. 
I have observed it in the following localities, which are beyond the 
eastern boundary, so far as I have yet seen it published. It is found 
widely exposed on a butte eight miles east of Greenwood, Yankton Reser- 
vation. Many blocks of it lie together, as though nearly in situ, about twa 
miles south-east of Niobrara, Neb., also a similar collection upon a butte, 
in Nebraska, five or six miles south-west of Yankton. A quarry of 
it occurs near Jackson's, half way between Niobrara and Creighton. A 
sandstone resembling it, but softer, is found about 100 feet below the 
summit of the hills at Wessington Springs, .Jerauld Co , Dak. The quart- 
zite stratum is quite easily recognized, and though thin, is quite persistent. 
I have taken the following notes on its altitude, Bijou hills, 2,000 feet 
above the sea; opposite the mouth of Pratt creek, 1,950; east of Greenwood,, 
1,675; 10 miles west of Niobrara 1,650; south-east of Niobrara, 1,525; near 
Jackson's, 1,675; south-Avest of Yankton, 1,500; Wessington Springs, 1,850, 
These are all barometric, and several only approximate estimates, but 
enough to indicate considerable dip to the east. 
I have not observed fossils sufficient to identify the formation, but from 
stratigraphical relations there is little doubt that it is later Teritary. Dr. 
Hayden referred the strata in Bijou hills to Pliogene [Loupfork]. Although 
not speaking particularly of the ((uartzite, he mentions "yellowish-white 
grit" and "gray sand with a greenish tinge." His experience with the 
field along the Niobrara and Loup Fork gives this opinion much weight. 
(See Prelim. Rep. Expl. in Neb. & Dak. 1855-57. p. 78.) 
Tabor, lowv, Dec. 8, 1888. J. E. Todd, 
Some remarks on professor Henry S. Williams' Report o;f the Sub-Com- 
mittee on the Upper Palmozoic (Devoriic), in The American Geologist, for 
October, p, 226. Professor H. S. Williams says : " In the final report, 
(1843, for the 3d district, p. 13,) Lardner Vanuxem proposed the name 
