THE CORALLIAN ROCKS 0¥ ENGLANJ). 269 



On the western slope of the hill, opposite St. Catherine's Chapel, is 

 situated the quarry (a) already noticed (p. 265) as representing the 

 Osmington Oolite ; and the first of the abrupt escarpments going east 

 is composed of the series representing the Trigonia-beds (b) ; while the 

 next escarpment presents us with higher beds, which will be described 

 in the sequel. 



On the broken edge of the first escarpment the following beds 

 may be traced, in descending order : — 



ft. 



1 . Thin flaggy limestones with abundant fossils 5 



2. Trtgonia-grit with Myacites 2 



3. Strong shelly limestone. 



4. White marl with Trigonia. 



5. Thin shelly limestone. 



6. Marl. 



7. Flaggy white Oolite 1 



8. Whitish marl. — 



The total being about 30 



In the space between the base of this and and the Oolite quarry 

 are some thin flaggy sandstones. Possibly Nos. 7 and 8 should 

 belong to the series below. These beds are most nearly paralleled 

 by those at Weymouth, but they chiefly illustrate the great vari- 

 ableness of the formation. 



The fossils collected from the upper part of these beds are inter- 

 esting and peculiar. Several of the species enumerated from the 

 Trigonia-beds of Weymouth and Osmington occur here, and we note 

 the following in addition : — 



Ammonites phcatilis (Sow.). 

 Ceromya inflata (Ag.). 

 Anatina, sp. (cf. undulata, Sow). 

 Myacites decurtatus (Phil.). 



Goniomya v-scripta (Sow.). 

 Mytilus jurensis (Bom.). 

 Pygaster umbrella (Ag.). 

 Acrosalenia decorata (Haime). 



Although the whole of the Corallian deposits have a distinct 

 character in the Weymouth area which can scarcely be paralleled 

 elsewhere, yet the most remarkably distinct are those which succeed 

 the beds already described. Immediately overlying the shelly lime- 

 stones of the Trigonia-beds, and without any gradual change, a 

 considerable thickness of clay is seen, reaching to as much as 40 ft. 

 at Sandsfoot Castle, somewhat less at Wyke, where about 12 ft. are 

 seen, and making a comparatively slight show at Linton Hill and Os- 

 mington. This clay, at Sandsfoot, is extremely calcareous, and con- 

 tains two indurated bands which may be described as a mixture of 

 lime, sand, and clay with a moderate proportion of ferrous carbonate, 

 disseminated pyrites, and carbonaceous matter. These two bands are 

 highly charged with fossils, often of a large size. In the intervening 

 clay the fossils are, on the contrary, dwarfed, as may be especially 

 seen in a large colony of deltoid oysters, which are extremely small. 

 The other fossils are Astarte supra cor allina (D'Orb), Corbula Des- 

 hayesea (Buv.), Nucula Menkei (Rom.), and small Areas and Trigonice. 

 In the harder portions a more numerous collection may be made, 

 including, in addition to those just mentioned: — 



