268 Mr. Lonsdale on the Oolitic District of Bath. 



constitutes the summit of the knovvl near Sand's Farm, and of the hill on 

 which is situated Pinhill's Farm : it occurs hkewise between the Lodge and 

 the Devizes Road in tiie new approach to Bowood from Quemerford. Its 

 first appearance as a continuous stratum is at Lockswell Heath ; whence its 

 western boundary may be traced by Peter's Farm^ Bowden Hillj the upper 

 part of Spy Park, Chitway, Nonsuch, Bromham (where the lower green-sand 

 and the calcareous g-rit are in contact), RowdeHill, Rowde Wick, Smythick's, 

 Barley-Hill Farm, and the western brow of Polshot Green to Polshot. Here 

 the continuity of the boundary is interrupted ; but the lower green-sand re- 

 appears on the ridge to the south of Worton,and may be traced thence to Stove- 

 Croft near Earl Stoke. The eastern boundary passes from Lockswell Heath 

 by Sandy Lane to Wands House, where it turns east, and follows nearly the 

 line of the Roman Road to Heddington Wick : at that hamlet it once more 

 takes a southern direction, and proceeds by Bromham House to Nether Street, 

 and by the brook nearly to Rowde Farm : afterwards it ranges by Conscience 

 Lane, the turnpike at the foot of Devizes Hill, and the eastern side of Polshot 

 Green, to the junction of the brooks flowing- from Whistley and Devizes. 

 Between this point and Cuckold's Green near Worton, the formation is con- 

 cealed ; but from the latter locality it may be traced by Rashley Common to 

 Crockwood Mill, and lastly by Pottern-Park Farm to Dues Water, Green- 

 land's Farm, and the knowl between that point and Long Street. 



Seend Hill and the summit of the two eminences on the north and south of 

 the main road between Seend Bridge and Foxhanger_, are outliers of the 



lower green-sand. 



Gait. 



The usual appearance of the gait in Wiltshire is that of a blue or yellowish 

 clay or marlstone. The former, which constitutes the greater part of the 

 formation, is generally of a friable nature, and yields readily to the frost. 

 Some of its beds effervesce, but others do not. It occasionally contains 

 nodules of indurated marl and small septaria. It is used in the manufacture 

 of bricks. The yellow clay, which is not of universal occurrence, is stiff, and 

 soapy to the touch ; it yields less readily to the frost, and is employed in the 

 making of tiles. Both the clays abound with minute spangles of mica. Near 

 the junction with the upper green-sand the gait sometimes becomes sandy, 

 and contains many particles of silicate of iron. 



Pyritical wood is the only organic body which I have found in the forma- 

 tion. 



The gait is concealed for the greater part of its extent by transported 

 matter from the Chalk Downs ; but it is visible at Blacklands, Calstone Wil- 



