Anticline in Southern Minnesota. — Focrste. 367 
The Cumberland sandstone. — In 1877, Prof. N. S. Shaler 
gave the name Cumberland sandstone* to a series of rocks 
along the Cumberland river. No section is described. Typi- 
cal exposures are said to be located above Burksville, in Cum- 
berland county, and thence the sandstone extends ii/a narrow 
area up the Cumberland to the southwestern border of Pul- 
aski county, and down the river to the southern edge of Ken- 
tucky. The sandstone is stated to "range considerably in thick- 
ness, and to attain thicknesses of 50 and even 100 feet. It is 
described as finegrained, commonly of greenish color, and en- 
tirely barren of organic remains. 
It is a difficult matter to determine what an author intend- 
ed to include under any term when no section is described 
and when no locality is mentioned at which the rock occurs 
typically, with the practical exclusion of other rocks to which 
the same description might readily apply. Under these cir- 
cumstances it must be assumed that the rock which topograph- 
ically is most conspicuous, and which geographically has the 
same general extension must have been the rock designated. 
The most conspicuous rock of Ordovician age between 
Burksville and Pulaski county, and the one which has the 
most general extension is the series consisting of the Platy- 
strophia bed, the Heterospongia bed, and the overlying thinbed- 
ded clays of clayey limestones. These are all referred here to 
the Lorraine. While the Platystrophia bed frequently con- 
tains fossils, these fossils are often absent in the upper part of 
the beds, or are very inconspicuous, owing to the fact that 
they never weather out of the clayey matrix, so as to be read- 
ily detected, but are seen only as cross-sections, where the rock 
has broken across the fossil, due to scaling in consequence of 
weathering. While these cross-sections could be readily de- 
tected if the rock were clocely examined, they might readily 
escape attention during a more hasty survey, especially dur- 
ing a rapid reconnaissance of the territory along a large river 
in a sparsely inhabited country, designed for the study of only 
the more striking economic features. 
The rock identified as Richmond at Forbush and Little 
Cub creeks does not occur at the other exposures visited farth- 
er down the river. 
* Geo\ogical Survey of Kentucky, 1877, vol. iii, New Series; consult 
also, 24th Report, Indiana Survey, pp. 57 to 60. 
