MIDDLE CHALK—NORTH DORSET. 425 
directly on a thin layer of buff-coloured marl and overlain by 
solid white limestone with few nodules. The upper part of it, 
passing up into yellowish nodular chalk containing Inoceramus 
mytiloides, can also be seen in a quarry in the plantation a quarter 
of a mile east of Shroton church. 
The best section, however, in this district is in a quarry about 
a third of a mile south-south-east of Okeford Fitzpaine, and it is 
remarkable as exhibiting a conglomeratic bed at the top of the 
Melbourn Rock. The beds seen are :— 
Middle 
Chalk. 
Lower 
Chalk. 
r 
■s 
( 
l 
ft. in. 
Hard white chalk, much broken, shaly at the base 6 0 
Hard yellow conglomerate (6 inches), consisting of 
chalk pebbles in shelly calcitic matrix, passing 
down into hard rough nodular chalk - - -30 
Several beds of firm white chalk, with hard yellow¬ 
ish nodules, separated by layers of grey shaly 
chalk.5 0 
Very nodular hard chalk - * - - - 1 3 
Loose nodular chalk between two layers of grey 
shale.0 9 
Massive rough and hard nodular chalk, with yellow 
stains round the nodules.4 0 
Smooth bedded chalk.0 9 
Thin layer of grey marl - - - - - - 0 3 
Blocky greyish-white chalk.8 0 
29 0 
The Middle Chalk crops out again on the southern side of Okeford 
Hill and forms an inlier in the Turnworth Valley, which runs 
southward to and beyond Houghton Winterborne, where Inocera¬ 
mus mytiloides has been found by Mr. Mansel Pleydell. 
To the south-west, between Milton Abbas and Alton Pancras, 
its boundaries have been mapped by Mr. C. Reid, and are shown 
on the recently issued map (Sheet 328, New Series). Its outcrop 
lies for the most part along steep slopes and nowhere occupies 
any great breadth of ground. 
The following information is from notes supplied by Mr. Reid* : 
The ridge between Hilton and Melcombe Bingham is capped by 
Middle Chalk, which is exposed in a large quarry by the road-side 
half mile north-east of Melcombe ; here about 30 feet of nodular 
chalk (including the Melbourn Rock) rests on smooth (Lower) chalk. 
In the Plush and Piddletrenthide Valleys the Middle Chalk 
occupies a rather wider space, and is exposed in several sections 
at the latter place ; north-east of the church a pit shows 35 feet 
of hard chalk, with a foot or two of yellow rocky chalk at the top, 
which is probably not far below the Chalk Rock. 
The Melbourn Rock, underlain by a two-foot bed of smooth 
yellowish chalk, is exposed in a lane half a mile north of Alton 
Pancras and again in the lane south of Bookham (see p. 115). 
*See also >l The Geology of Dorchester,” Mem. Geol. Survey, by G. Reid, 
1899, p. 8. - 
