86 Mr. Weaver’s Geological Remarks. [Ave. 
coarser grained, or of conglomerate, arranged at certain dis-) 
tances in parallel order. The fine-grained sandstones yield. 
large flagstones. - 
The fine-grained clayey sandstone passes into slaty micaceous: 
sandstone of difterent degrees of firmness, containing numerous 
scales of white mica. It passes also gradually into ¢ndurated. 
clay, which is mostly slaty, and either pure, or sandy and firm, 
and of red, green, or grey colours; the substance being gene- 
rally intimately mixed with minute scales of mica. Beds of this 
clay, which are often ofthe nature of c/ay mar/, and occasionally 
contain lighter-coloured portions of a calcareous quality, are 
frequent m the old red sandstone of Mansfeld. 
The clay and clay marl are found likewise in thin layers 
between the sandstone beds, of red, grey, green, and blue. 
colours, and sometimes also included in them im the form of 
ovoidal or flattened elliptical nodules, then resembling, as 
Freiesleben observes, the clay galls of the new red sandstone 
formation. 
Beside the colouring matter of the old red sandstone derived 
from oxide of iron, diftused through its substance, brown and 
red iron ochres are occasionally found in it in spots, round por- 
tions, and thin streaks.* 
Grains, slight layers, and indeterminate portions of compact, 
scaly, and ochraceous red iron ore, have also been met with; 
and near Mansfeld, Freiesleben noticed in the sandstone com- 
pact red iron stone in the form of the stems of reeds. 
Associations of the Old Red Sandstone—a. Coal; 6. lime- 
stone; c. porphyry and amygdaloid ; d. coal fields. 
a. Coal.—Near Grillenberg, in Sangerhausen, a slight coaly 
seam, from a half to one and a half inch thick, has been foundin 
the old red sandstone ; and a somewhat similar appearance is 
said to have occurred near Mollendorf, in Mansfeld.+ 
b. Limestone.—Oft the occurrence of this mineral in subordi- 
nate beds in the old red sandstone, the following instances are 
given: near Cressfeld, a bed of compact, splintery, and partly 
foliated granular limestone, of greyish colours, with interspersed 
lamin of white calcareous spar: at Vatterode, Wimmelrode, 
and Mollendorf, a bed, eight to ten feet thick, of compact fine 
splintery limestone, of brownish-red, greenish, and reddish-grey 
colours, with disseminated spots of calcareous spar, and veins 
of the same substance ; it was formerly wrought for marble, and 
sent to Berlin: near Rothenburg on the Saale, limestene dis- 
posed in the sandstone iv thin beds, of a red or hght-grey 
colour, minutely granular cr compact, and containing terbratu- 
* The precedmg general description of the sandstone, slaty sandstone, clay, and 
clay marl beds of Mansfeld, with nodules also resembling clay galls, might almost 
serve word for word, for that of the old red sandstone on the banks of the Severn, in 
Gloucestershire, as well.as in many respects for that of Tortworth and Milbury Heath. » 
+ A parallel instance of the casual occurrence ¢f imperfect coal in the old red sand- 
stene may also be found in England, e. g. in Portishead Point, near Bristol, 
