LOWER CHALK—OXFORD AND BUCKS. 
179 
Part of the same zone is exposed in the limekiln quarry on Beggars 
bush Hill, south-west of Ewelme, the pit being about 40 feet 
deep, and the upper 30 feet being of whitish chalk. 
The same chalk is seen in a small pit south of Lewknor, in the 
railway cutting south-east of that village, and in the cuttings by 
Aston Bowant Station, but they present no features of interest, 
and fossils are rare. 
The very highest beds, with the subzone of Actinocamax planus, 
are well exposed at two places near Wallingford. A quarry on 
j. U At/ 
White Hill, east of North Stoke, shows : — 
ft. 
Melbourn Rock ----------5 
f Buff-coloured laminated marl, with Act. 'plenus - - 1 
Marls ® ai *d compact white chalk ------ l-ii 
lGreenish slialy marl, Rhynchonella sp. - about -3- 
Blocky white chalk, with patches and mottlings of grey mate¬ 
rial near the top, giving it a brecciated appearance about 10 
The other section is in a deeply-cut cart-road by Coldharbour 
farm, east of Crowmarsh, and shows : — 
ft. 
Melbourn Rock ------- about 3 
g I i Soft grey laminated marl ----- „ 1 
-jir V - Hard white compact chalk - - - - - ,, 1 
dr s* [Thin parting of grey marl. 
Firm white chalk ------- seen for 5 
South of Bledlow, in Buckinghamshire, there is a quarry just 
above the outcrop of the Totternhoe Stone, showing tough greyish- 
white blocky chalk with large Ammonites,— Am. [Acanth.] 
rotomagensis and Am. [Acanth.] sussexensis. 
The best section in Bucks, however, is in the large chalk pit at 
Butler’s Cross, west of Wendover. The beds here seen are the 
following : — 
ft. 
Middle chalk and Melbourn Rock ------ 
rSoft grey laminated marl ------ 
J Hard white compact chalk, thinning out southward - 
I Soft grey shaly marl ------- 
IGreen gritty shale, thinning out southward - 
/Hard rough chalk, mottled grey and white, passing 
into next --------- 
Rather hard white chalk, breaking into massive 
Act. 
plenus 
Beds. 
5 - 
■+0 
co 
e 
CO 
§ 
rs CO 
l 'C> 
angular blocks with smooth surfaces 
rO 
o 55 
O 
S3 
Tough 
grey 
chalk 
seen for 
12 
3_1 
4 1 
0-1 
0-1 
i-H 
2 ^ Parting of shaly marl 
0 5 s Tough grey bedded chalk ------ 
Hard rough grey chalk, with grains of glauconite and 
many green-coated nodules - 
9 
o 
The remarkable part of this section is the thinness of the white 
chalk at the top of the zone and the signs of erosion presented by 
its upper surface. Instead of the usual 30 or 40 feet of white chalk, 
there is here only 9 or 10 feet, and the total .thickness between 
4219. N 
