572 Geological Society. 
ably with the coal measures ; but at the latter locality they are stated 
to be overlaid unconformably by the upper new red sandstone, 
The immediate vicinity of Manchester consists of upper new red 
sandstone, occupying the cavity formed by a flexure in the underlying 
deposits, and is generally supposed to be unconformable to them. It 
is very soft when first exposed, but hardens by exposure to the atmo- 
sphere ; and is occasionally marked by belts and nodules of white 
sand, and in the lower part contains rounded fragments of granite, 
quartz, and other older rocks. No organic remains have been no- 
ticed in it. 
The upper red marl is exposed only at Collyhurst, about a mile to 
the north-east of the Manchester Exchange, in the old road to Blake- 
ley; but it has there yielded a greater number of fossils than has been 
found in any other bed of the superior divisions of the new red sand- 
stone group in England. 
The deposit extends about a hundred yards, and at one of the 
points examined presented the following details : 
Top a. Variegated marls, no organic remains .... 6 inches. 
b. Strong, red marl, traversed near its centre 
by a thin layer of fragile bivalve shells... 5 —— 
c. Light-coloured, calcareous marl, marked 
with lines and spots of a beautiful red... 3 —— 
d. Light-coloured, calcareous, strong marl, 
containing an immense number of imper- 
fect casts of bivalves and perfect univalves 5 —— 
When the marl is first excavated it crumbles 
under the touch, but after exposure for a 
short time, it is fractured with difficulty. 
e. Clay, striped red and white, and containing 
GADts OF Dayal Ves igi Gh Litera aes teste ar- Cac's 4—— 
f. Light-coloured marl, similar to No. 4, and 
inclosing numerous casts of bivalves and 
LINIVALVES: w1oik)e ie -lole lsteteieedoks canucteels 3 — 
g. Variegated marl, with an immense number 
of univalves and bivalves, 2 inches ..... 2— 
h. Indurated red marl, mottled with streaks of a 
greenish colour. The upper part contains 
numerous casts of large bivalves, and the 
light-coloured streaks also inclose casts 
of bivalves and univalves. Few shells are 
found below the depth of one foot, though 
the author had the bed penetrated to the 
depth of 29 feet, when an influx of water 
prevented them from boring any further. 
The rhomboidal fracture, so characteristic 
of the red marl, was very observable in 
this ibedo: stool te isteloRre > wttietnie te -. 29 feet. 
With respect to the geological position of these fossiliferous marls, 
the authors are fully satisfied that the deposit reposes on the upper 
