LOWER CHALK—NORTH DORSET. 
105 
Beds 
1 and 2. 
Bed 
3. 
Bed 
4. 
Pecten orbicularis, Sow. - 
X 
,, elongatus, d'Orb. - 
- 
- 
X 
Plicatula inflata, Sow. - 
X 
- 
X 
Spondylus latus, Sow. - 
X 
- 
- ! 
Trigonia vicaryana, Lyc. - 
— 
— 
X 
Rhynchonella grasiana, d'Orb. - 
- 
X 
X 
„ dimidiata, Sow. - - - 
X 
— 
— 
Catopygus columbarius, Lam. - 
- 
- 
X 
Discoidea subuculus, Klein - 
— 
— 
X 
Holaster subglobosus, var. altus, A g. 
- 
- 
X 
Plocoscyphia sp. ----- 
- 
- 
X 
Stauronema Carteri, Sollas - 
— 
- 
X 
There are several exposures round Melbury Hill, which together 
make up almost a complete section through the Lower Chalk. The 
lowest 10 or 12 feet is seen above the passage-beds in the quarry 
described above, and beds which may be regarded as an upward 
continuation of these are exposed in a small pit by the cottage south¬ 
west of the hill. These are : — 
ft. 
Soil containing remains of a layer of hard chalk - 1|- 
Grey blocky chalk marl ------ - 2 \ 
Course of hard grey chalk.f 
Grey chalk marl, passing down into bluish sandy marl, with 
conchoidal fracture, coming out in ball-like lumps - - 10 
14f 
Between these two exposures there is a large quarry on the west 
side of the hill, a cartway leading to it out of the main road. At 
the entrance to this cartway the basement beds are seen. At the 
entrance of the quarry there is soft marly chalk, with 7 or 8 courses 
of hard greyish chalk, the usual southern type of Chalk Marl. 
Higher up are massive beds of firm blocky chalk, alternating with 
layers of soft marly or shaly chalk. Still higher the chalk is entirely 
blocky, and becomes nearly white, passing, no doubt, into that of 
the zone of Holaster subglobosus (see p. 108). 
A quarry at East Compton, about 20 feet deep, shows grey 
marly chalk in the lower part, with Am. [Schloenb.] varians, and at 
top whiter chalk, with several beds of hard chalk, one nearly white, 
but the topmost greyish-white and a foot thick. 
A good idea of the whole Lower Chalk succession can be gained 
from exposures by the lane leading up to Sutton Hill. 
The Chalk Marl can also be examined in a quarry at the north¬ 
west end of Hambleton Hill, near Child Okeford. The bottom of this 
is probably about 30 feet above the Chloritic Marl, and the total 
thickness of the Lower Chalk may be 160 feet. The beds on the 
east side of the quarry consist of soft blue and grey sandy marls, 
/ 
