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THE CRETACEOtTS ROCKS OF BRITAIN. 
CHAPTER XXXIII. 
THE MIDDLE CHALK IN THE INLAND PARTS OF 
DORSET, SOMERSET, AND DEVON. 
The Chalk areas of Dorset, Somerset, and Devon, once of course 
a continuous tract, are broken up toward the west into a series 
of outliers, and the Middle Chalk does not enter into all of these, 
though it occurs in all three counties. Thus they may be con¬ 
veniently treated in one chapter, but we shall keep the account 
of the Dorset areas separate from that of those in Somerset 
and Devon. 
North and West Dorset. 
The main outcrop of the Middle Chalk enters Dorset about 
two miles south of Shaftesbury, passes southward along the slope 
of the escarpment to the valley of the Stour at Stourpaine and 
thence westward as far as the Chalk extends through the country. 
Along the northern side of the Dorchester basin, however, it 
often occupies the top of the escarpment ridges, passing thence 
into the valleys which drain southward and running down them 
for several miles before disappearing beneath the Upper Chalk. 
Its thickness in the northern part of the county is about 100 
feet, and about the same in the west on Toller Downs, but near 
Maiden Newton it appears to be rather less (? between 70 and 80.) 
Melbourn Rock of the usual character continues to form the 
base of this division as far as Melcombe Bingham, but west of that 
a bed of hard smooth chalk conies in between the Belemnite 
marls and the base of the Melbourn Rock. This thickens to 
the westward, and swells out in places to 12 or 14 feet, the Mel¬ 
bourn Rock at the same time losing its specially massive and rocky 
character and becoming merely a rather hard nodular chalk. 
The smooth chalk is evidently the equivalent of that which 
occupies the same position in South Dorset. 
Good exposures are not very numerous, and we shall mention 
such as exist, taking them from east to west, without sub-division 
into zones. 
Stratigraphical Details. 
The outcrop of the Melbourn Rock can be found in many of 
the roadways leading up the slope of the escarpment between 
Melbury Hill and the valley of the Stour. It is well exposed in 
the road east of Sutton Waldron at a height of about 450 feet 
above O.D., hard nodular rock with greenish stains resting 
