218 
SILURIAN OUTLIER WEST OF CAER CARADOC. OCT., 1892. 
Vertical Section.— The sequence of the Shropshire 
Silurian strata, with their approximate thicknesses, as shown 
on the sections of the geological survey, is as follows :— 
Upper Ludlow Rock ... ... about 400 feet. 
Aymestry Limestone 
Lower Ludlow Shales 
Wenlock Limestone 
Wenlock Shales 
Tarrannon Shales ... 
Woolhope Limestone 
“ Mayliill ” Sandstone and Conglomerate 
> 1 
5 5 
100 
650 
250 
1,400 
125 
25 
50 
>> 
» » 
5 > 
») 
Total ... „ 3,000 ,, 
Absence of Limestones West of the Older Rocks. —The 
limestones are generally present in the east of the county, 
but after passing the line of the older ridges of the Long- 
mynd, Stiper Stones, and Shelve districts they are no longer 
met with ; the conditions necessary for the formation of 
thick beds of limestone were apparently absent from that 
western area during the Silurian epoch. 
Rock Exposures of the Outlier. —In order to keep facts 
and theory as much apart as possible, I will now proceed to 
describe the principal exposures of rock in the outlier, which 
are indicated by various letters on the map (Plate V.) ; and 
subsequently will endeavour to point out some of the 
inferences that may be drawn from them. 
In a small wood called Hough’s Coppice, about half way 
between All Stretton and Caer Caradoc, beds of nodular and 
massive limestone separated by shale may be seen dipping 
eastwards at an angle of about 45° to 50°. Similar beds are 
to be found in several positions southwards of this point (at 
K, M, and N on the map), forming a somewhat detached line 
of prominences, the last being about an eighth of a mile N.E. 
from the railway station. 
From these beds the following fossils have been identified : 
Halysites catenularis ; Phacops caudatus ; Serpulites longis- 
simus; Stropliomena trapezoidalis ; Leptcena laevigata ; 
Gromphoceras obovatum ; there occur also many other corals, 
but the species have not yet been determined. 
About 100 yards eastward of this broken line, and near 
the middle of its length, in a little clump of Scotch firs 
(marked L on the map), a small stream exposes some blue, 
clayey rock (having approximately the same dip, viz., 45° to 
the east), from which the following fossils have been 
obtained:—Monograptus colonus; ditto var. basileus; M. 
Nillsoni; ditto var. ; M. Roemeri; ditto var. ; Retiolites 
sp. nov.; Acidaspis coronatus; Phacops caudatus; P. 
