216 Dr. FiTTON on the Strata below the Chalk. 



able at the top and another at the bottom of the sands. The curves and contortions of the . 

 limestone beds in the Purbeck strata, where they alternate with clay, are strongly contrasted 

 with the parallelism and regularity of the more uniform parts of the series, both in the sands 

 above, and the Purbeck and Portland formations below ; the difference being probably ascribable 

 (as Mr. Conybeare, I believe, has remarked,) to the effect of lateral pressure, upon a mass con- 

 sisting of folia which differ so much in their power of resisting flexure and compression, as the 

 limestone and the clay. 



Luhoorth Cove. — The relative space occupied by the different groups below the chalk, on 



the east side of this Cove, is as follows: (See PI. X.a. No. 10. ; and X.b. fig. 7.) 



Ft. In. 



1. Upper Green-sand, including large concretions of chert 76 



2. Blue Clay (Gault), occupying a depression, in part covered with grass 66 



3. Wealden. Clay and sand: — Feet. 



a. Reddish sand and clay 122 



b. Sand of various shades, yellowish and brown : about the middle are beds^ 



of coarse conglomerate, consisting of fragments of translucent quartz and 



of blackish flint ) 281 



[A coating of diluvial gravel extends from the chalk to about the middle 

 of this space, where the cliff is about 40 feet high.] ) 



c. Reddish sand and clay. [The cliff is here 10 or 12 feet lower,] 80 



d. Dark-brown sand, including fragments of lignite and of fossil wood. T 

 [Large Unios and a small Paludina (elongatal) are found near this place.] J 



e. Grey and whitish sand 15 0\ 



Greenish clay and sand. [Cliff about 30 feet high.] 26 J 



f. A band of red clay and of dark-brownish matter 



g. Yellowish sand 



h. Dark carbonaceous sand 



4> 

 41 



M50 



i. Variegated sand and clay, greenish and reddish. [A depression here in -i 



the outline of the cliff. At the lower part beds of compact grey lime- I 66 



and clay. Surface in pan concealed and covered with grass.] J 



Total, about 600 



4. Purbeck strata: estimated at 150 yards ; cliff about 80|fect high. [Distinct ledges of ^ 



coarse sand-rock, including much green matter and a thick species of Unio, are 

 quarried near the top of the formation. On the shore were fragments of beds of 

 fibrous carbonate of lime, 7 to 8 inches thick] _ 



5. Portland- stone (estimated at 80 yards) 240 



The Upper Green-sand is very distinct in this section. The place of the Gault is indicated by 

 a slight depression, which is continued in the grassy hills on the east of the Cove. The Lower 

 Green-sand may, possibly, be included in the general mass of sand, 3. a. ; but the Weald claij is 

 not distinguishable. Below the mass of yellowish and ferruginous sands, 3. b., is a considerable 

 extent of variegated clays, comprising beds much charged with carbonaceous matter; the whole 

 clearly referrible to the Hastings sands. The transition thence to the Purbeck strata is not 

 distinctly seen; but some of the beds, 3. i., of grey uniform limestone, alternating with clay, near 

 the junction, resemble those of the " lime-works " on the north-west of Battle, which are sup- 

 posed to be the lowest members of the Hastings series. The top of the Purbeck on the east of 

 the Cove contains very numerous Unios in coarse green sand-rock : and on the west side a bed 

 of greenish slaty stone, in the upper part of the series, consists of oolitic particles, and contains 

 Cypris. Near the junction of the Purbeck with the Portland stone, the site of the "Dirt-bed", 

 which in the Isle of Portland contains silicified trees and Cycadeae, is vei-y distinctly seen. 



