258 LOWER OOLITIC EOCKS OF ENGLAND : 
So far as I know there is no difference of opinion on this 
subject of the passage of Fullonian or Fuller's Earth into Great 
Oolite. 
In Dorsetshire and South Somerset the Fuller's Earth is divi- 
sible into three stages, upper and lower divisions of clay, separated 
by the Fuller's Earth Rock, a marly limestone which forms a 
marked feature in the scenery between Sherborne and Wincanton. 
Northwards by Frome the Fuller's Earth Rook may be readily 
traceci, but towards Bath it becomes much attenuated. Indeed, an 
examination of the Geological Survey Map (Sheet 19) suggests 
that the Fuller's Earth Rock might represent the Great Oolite, 
for curiously enough the mapping of the Rock ceases in one 
place near Stoney Littleton, where the Great Oolite comes on. 
Moreover the texture of the Fuller's Earth Rock is very similar 
to some of the soft beds of white earthy limestone that form the 
upper portion of the Great Oolite in East Gloucestershire and 
Oxfordshire. 
The notion that the two might be portions of one formation 
possessed me for some time, but it was dispelled when I came to 
examine the ground at Bath. In several places where the Fuller's 
Earth Rock has become too attenuated to be shown on the map, 
it is nevertheless present ; as I found to be the caire between 
Wellow and Norton St. Philip; as the Rev. H. H. Winwood 
pointed out to me on the slopes of Lansdown, and MS Prof. Hull 
has shown to be the case at Slaughterford, N.E. of Bath. 
It is therefore clear that the Great Oolite overlies the Fuller's 
Earth Rock in the neighbourhood of Bath and Bradford-on-Avon. 
At the same time this Rock maintains a fairly uniform character 
of white marly limestone, and contains a similar assemblage of 
fossils, in its range from Dorsetshire to Somersetshire, while it 
merges upwards and downwards into the marly clays of the 
Fullonian formation, and is of varying thickness and importance. 
The evidence before us, then, is that the Great Oolite, and 
more especially the Stonesfield Slate, pass downwards into the 
Fullonian. Bearing this in mind, it is worthy of note that the 
Fuller's Earth Rock does not extend far north of Bath (in the 
Ootteswold regions) where the Stonesfield Slate is developed at 
the base of the Great Oolite. 
Here I may mention that in. Normandy, the Fuller's Earth 
Marls appear to pass laterally into the Caen Stone, a rock 
yielding Saurian and other remains that serve tc connect it with 
the Stonesfield Slate. The strata just mentioned are overlaid by 
the Great Oolite. The irregular and varying characters of the 
beds in that country have been pictured by M. Deslonwchamps ;* 
but as the authorities are not of one mind on the subject of the 
grouping and correlation of the strata, we shall perhaps do best 
to discuss the stratigraphical relations of our rocks on independent 
grounds. 
* Etudes sur les Etages Jurassiques Inferieures de la Normandie, 1864. 
