132 
THE CRETACEOUS ROCKS OE BRITAIN. 
The Am. Mantelli zone sets in again, however, at Rousedon, and 
is exposed near the top of the old quarry in the ciiff, a quarter of 
a mile south of the mansion. The section here is as below : — 
ft. in. 
Middle Chalk. Whitish chalk, blocky above, rough and nodular 
in the lower beds (Rh. Cuvieri zone)- - - - 15 0 
C. Rough glauconitic and quartziferous chalk - - - 0 9 
B k A. Glauconitic limestone with phosphatic nodules in 
the upper part ; compact and shelly bfelow, with 
Am. [ScM.\ varians , Am. \Acanth.\ Mantelli , etc. - 2 0 
Upper Greensand ------ about 37 0 
Here Beds A and B form a single course of hard glauconitic lime¬ 
stone with clearly-defined upper and lower surfaces. This lime¬ 
stone can be followed along the Howlands cliffs till the ground falls 
away into the valley which separates these cliffs from those of 
the Bindon landslip. It can be reached at many points in the 
great cleft of this landslip, but the relations of the beds are some¬ 
what different here; the lower limestone (A and B) is thinner (about 
18 to 20 inches only), and the Bed C thickens to about 18 inches, 
becoming also hard and more clearly separated from the chalk 
above. 
The lower bed is fine grained, compact, and shelly, correspond¬ 
ing chiefly with Mr. Meyer’s Bed 11, without any coarse grit at 
the base to represent his No. 10, and with only a few inches at the 
top that contain greenish lumps, and seem to represent Bed B (his 
No. 12). At the base of C there is a layer of phosphatic nodules 
and fossils, but in the mass of C no fossils except Rhynehonella 
Cuvieri, var. Wiesti, and Galerites castanea were found, the former 
being common. 
Beyond the landslip valley and at the west end of a fine cliff 
facing south, the bed is again accessible, and the succession is as 
follows : — 
ft. in. 
Hard rough nodular chalk (Turonian).100 
h C. Very hard gritty limestone, consisting of quartz and 
glauconite in a chalky cement - - - - - 0 9 
A & B. Hard glauconitic and sandy limestone, with a layer 
of phosphate nodules at top - - - - -13 
Upper greensand—rough yellowish sandstone - - - 8 0 
Here the two glauconitic limestones are thinner than they are 
200 yards further east, and there is less separation between them 
than usual, so that they seem to form one bed about 2 feet thick with 
a layer of phosphatic nodules about 9 inches from the top. It is, 
however, only the lower bed which represents the zone of Ammonites 
Mantelli. 
Beyond this the chalk retires from the edge of the cliff-slope 
for a space, but comes in again at Haven Cliff, where the Cenomanian 
limestone is nearly 2 feet thick, and contains Pecten asper, Rhyn- 
chonella dimidiata, &c.; the usual layer of phosphate nodules 
occurs above it. 
