GEOLOGY OF CHILHOWEE MOUNTAIN, IN TENNESSEE. 81 
This vertical relation may have been due to any one of 
three causes: (a) contemporaneous deposition of limestone 
and sandstone in adjacent areas; (£) a thrust fault bringing 
the limestone over the sandstone and traversing the beds of 
both; (c) deposition of limestone over an irregular basin in 
the sandstone. 
(1) In favor of the first hypothesis, that of contempo¬ 
raneous deposition, may be cited two apparent transitions 
between limestone and sandstone. The first, on the line of 
section B, is quite peculiar. The limestone there is very 
silicious, with both secondary quartz and rolled quartz 
grains; it occupies a narrow ravine between two sandstone 
knobs, and is directly in the strike of the sandstone masses. 
(2) The second, near the line of section G, is apparently 
a vertical passage from sandstone through sandy limestone 
into massive limestone. At the contact of sandy limestone 
and sandstone there is a difference of 60° in strike between 
the two, and a small bed of black, calcareous shale fills in 
the irregularities of the sandstone. This slate is associated 
with the limestone by its calcareous nature, and contains 
nodules of limestone and fragments of sandstone as large as 
the fist. The sandstone pebbles are grayish white, fine¬ 
grained, and similar to the Chilhowee sandstones. There is 
no known formation previous to the dolomite whence they 
could be derived except Chilhowee. These pebbles prove 
that the slate and overlying limestone came after the sand¬ 
stone, and that some of the sandstone was subaerial at that 
time. The slate bed proves an interruption and change in 
deposition— i. e. } that there was no transition. 
Comparison of the two contacts with reference to the pre¬ 
cise horizon of the limestone and sandstone in contact brings 
out the further fact, which cannot be reconciled with simil- 
taneous deposition— i. e., the limestone touches the middle 
sandstone of Chilhowee in section B and the upper one near 
section G. The range of the contact between these horizons 
in the Chilhowee series is 700 feet. 
(3) Even greater is the distance in sections C and G. In 
