254 Mr. Lonsdale on the Oolitic District of Bath. 



The western boundary of the great oolite ranges along the brow of the 

 downs from Tog Hill near Wick, to Huddock's Hill near Dunkerton ; but 

 between these localities it is frequently intersected by deep valleys, which occa- 

 sionally isolate the hills, and then render the oolitic table lands, by which they 

 are surmounted and distinguished, outlying- portions. A line drawn nearly 

 east from Huddock's Hill to Hinton Field Farm, about mid-way between 

 Hinton and Norton, would define the southern boundary of the great oolite. 

 At the Farm just mentioned is a small quarry in this formation ; and a narrow 

 band, apparently belonging- to it, extends around a projecting knowl opposite 

 the quarry. Beyond this point the great oolite cannot be traced. It might 

 however be conceived, that the termination is only a lithological change, and 

 that here, as elsewhere, the great oolite merely assumes the characters of the 

 forest marble. The thin bed of sandy clay and grit which constitutes the 

 bottom of the latter formation, and the Bradford clay, attain under these cir- 

 cumstances a great importance. At Norton, and through the whole of the 

 southern range of the district, either one or the other of those strata, is visible 

 resting on the fuller's earth, and thus proves clearly that the disappearance 

 of the great oolite is not deceptive but real*. 



The accompanying diagram will illustrate the relative positions of the three 

 formations, and the thinning out of the intermediate one. 



Sandy clay and grit, 



The superior boundary of the great oolite, or that which defines its separa- 

 tion from the Bradford clay and forest marble, extends in an undulating hne 

 from Yatton Keynell by Giddy Hall, and the brow of the hills overhanging 

 the Box brook to the Chippenham road, which it crosses to the westward of 

 Pickwick : thence it follows the curvature of the hills, but keeps a little to the 

 east of their escarpment, to Wadswick and the Devizes road, which it passes 

 near Wormwood Farm : from this point it turns westward, and ranges along 

 the descent which bounds Kingsdown and Farleydown on the south, and 

 crosses the Bradford road a little above Monckton Farley : it afterwards de- 



* The points most favourable for examining the connection of the lower grit with the fuller's 

 earth, are : the top of the Lane leading from Falkland Knowl to Stone)' Littleton ; the descent of 

 the road from Frome towards Wells ; Buckland Denham ; and the brow of the hill above Green 

 Parlour near Radstock. 



