3822.) Mr. Weaver’s Geological Remarks. 89 
On the Wettin coal field, Freiesleben observes, that “ it is 
imbedded in the rothe todtliegende, being both covered by, and 
reposing on, rothe todtliegende.” The coal has been pursued 
for 70 fathoms beneath porphyry, and this porphyry is also 
proved to lie in the rothe.todtliegende, not only by a distinet 
graduation from the one rock into the other, but by the former 
appearing in separate beds in the latter. 
b. The Lobegiin Collieries (vol. iv. p. 260—264).—These are 
situated among hills of porphyry, occupying hollows and dells, and 
apparently forming a mantle round porphyry. Hence no gene- 
ral range or dip can be given; the latter is often at a high angle, 
from 50° to 80°. Itis stated that, wherever accurate observa- 
tions have been made in these collieries, the porphyry has 
always been found subjacent to the coal field. The coal beds 
here, as far as sunk into, consist as under : 
1. Vegetable soil, with sand and conglomerate, 21 inches 
thick. 
. Clay marl varying from 21 to 32 inches. 
. Conglomerate, 7 to 21 feet. 
. Coal smut, 3 to 6 inches. 
. Blue clayey rock, becoming gradually thicker in descend- 
ing, 21 inches to 14 fathoms. 
. Coal, 7 feet to 9 feet 8 inches. 
. Blue clayey rock, 21 inches to 14 feet. 
. Blue sandy rock, beyond which the works had not ex- 
tended. 
The coal seam is divided into three beds by two intervening 
layers of shale, one of which is 10 inches, and the other from 
5 to 10 inches, in thickness. In another part of the field, a 
second seam of coal has been met with, from 21 to 32 inches 
thick. 
c. At Kathau the coal sandstone is found supporting porphyry 
on its southern side in a distinct manner (vol. iv. p. 118). At 
Gerwitz, a small coal trough reposes on porphyry; and between 
Halle and Giebichenstein the coal is imbedded in porphory. 
(Vol. iv. p. 293.) 
d. Beside these facts, Schulze states in his map, appended to 
Freiesleben’s work, that the coal at Raunitz reposes on porphyry, 
while to the E. of Brachwitz, it appears to underlie porphyry. 
Now, combining these observations, it is perfectly clear that 
in the coal tract of the Petersberg, between Halle on the S. and 
Kathau on the N., the coal formation alternates with porphyry ; 
and yet it is stated (‘ Outlines,” p. 469), that these porphyries, 
thus connected with the rothe todtliegende, belong to the same 
era as the new red conglomerate or sandstone of England ; posi- 
tions quite irreconcileable with each other. 
3. The South Western Coal Field.—After the detail into 
which we have entered, it may be sufficient to observe that in 
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