294 Dr. FiTTON on the Strata below the Chalk. 



the north of that village, and Lillihoe In Hertfordshire, an Ordnance Station 604 feet above 

 tlie sea. 



The Lower chalk, on which the village of Dunstable is placed, runs from Totternhoe on the 

 south-west of the main-road, through Houghton Regis, Upper Sundon, and Streatley, on the 

 north-east of it. 



On the north-east of Totternhoe mines are driven into the hill at the bottom of the chalk, for 

 the purpose of extracting a bed of uniform light greenish-grey, marly and sandy, firestone, from 

 seven to ten feet thick. The strata are traversed by numerous cracks, which seem to pervade 

 the hill, and indicate disturbance, — or perhaps the effect of subsidence. 



The Gault, in Smith's map of Buckinghamshire, occupies a large part even of the higher ground 

 between Whitchurch and Wing. The Lower green-sand runs out without interruption from Whit- 

 church to Winslow, and is continued thence by Drayton, Parslow, and Soulbury, to the south of 

 Leighton. On the north of that line, a denudation on the course of the Little Ouzel river having 

 cut down to the subjacent clay, breaks in upon the outcrop of the sands, which would otherwise 

 have been continuous from Winslow to Brickhill, and the mass of the Woburn sand-hills. Be- 

 yond the two tracts at present continuous, several outlying patches of sand, some miles distant 

 from each other and from the general escarpment*, are ascribed to this formation in the map ; 

 all of which, as well as the wider tract between Winslow and Leighton, deserve examination, for 

 the purpose of ascertaining whether any of the Wealden beds are to be found there. 



The greatest expanse of the Lower green-sand in the midland counties, occurs between Leighton 

 and Ampthill in Bedfordshire ; rising, at the Ordnance station on Bow-Brickhill, to the height of 

 683 feet above the sea, — or about 430 feet above the lowest point in the valley on the west of the 

 escarpment near Fenny Stratford. One of the most remarkable subordinate beds of the forma- 

 tion in this neighbourhood, is Fuller's earth, which, when I was there (in 1824) was brought out 

 by mining from the north-west escarpment of the sand-hills, near Hogstye-end, between the main 

 road from Woburn to Northampton, and that from Hockliffto Stony Stratford. 



Fuller's earth Pit, near Woburn. 



Ft. In. 



1. Sand; nearly uniform, greenish-grey, and yellowish, including consolidated masses"! .,,„ 



of sand-rock, and dipping to the east and south about J 



2. Fuller s earth. 



a. " Top" of inferior quality ; not diffusing itself in water till after it has 1 



been dried ; unfit for the purposes of the clothier 3 I 



h. Ferruginous ? clay about 1 }• 1 2 



c. Fuller's eartli, of the best quality, very light olive green; (sold at the 



pit-mouth to cloth-manufacturers, for one shilling per cwt.) . . 7 ft. to 9 j 



4. "Bottom"; hard quartz or sand-rock ; the equivalent, probably, of the chert of the"! ^ 



Kent and Surrey sand-hills 2 ft. to j " 



5. Sand, like 1 ; thickness not ascertained. 



The Geological place of the Fuller's earth is here, therefore, nearly the same with that of 



* These outliers are represented on the Buckinghamshire map by patches of colour, each 

 about h-Ai a mile in diameter, at Roundhill, Whaddon, Totternhoe, Wroughton, Milton-Keynes, 

 Broughtoii, Moulsoe, and Astwood. In Mr. Greenough's map, (1st edition,) both Winslow and 

 the heights of Whadden Chase on the north of that town form a portion of the tract coloured as 

 Oxford clay ; but this, no doubt, requires correction. 



