THE CORALLIAN ROCKS OE ENGLAND. 265 



by the impervious clays below. A more abundant supply of the 

 cementing materials might have formed a continuous bed. By these 

 the series may be best traced inland, as at Broadwey, Bodwell Sta- 

 tion, &c. and near Abbotsbury. To the east of Osmington the grits 

 encroach on the sands below, and finally appear to drive them out, 

 the marly beds above becoming at the same time thicker, the total 

 being in this instance less than at Weymouth, namely about 18 ft. 



The fossils of the Grit are Cucullcea corallina (Ph.), Pecten 

 qualicosta (Et.), Gervillia aviculoicles (Sow.), Cerithium, sp., Lucina, 

 sp., Exogyra nana (Ph.), and Trigonia corallina (Ag.) — a fauna 

 which, though small, has relations both above and below, but mostly 

 with the beds above. 



At Wyke, by the Fleet, this series can scarcely be recognized, it 

 being stratigraphically represented by false-bedded calcareous sand- 

 stones with their slope to the west — that is, lying on the edge of 

 beds on the same parallel to the east. 



The next series in the ascending order is an important and inter- 

 esting one. It is composed of marls and oolites in varying pro- 

 portions. At Osmington it contains a beautifully compact and 

 uniform single bed of white, fine-grained oolite, of a thickness of 

 12 ft., which we call the " Osmington Oolite." This, in physical 

 character, is not unlike some of the Great-Oolite beds of Minchin- 

 hampton, being remarkably uniform in its structure. It is a 

 tolerably pure limestone for this district, but still somewhat sandy ; 

 it is highly fossiliferous at Osmington, though the thicker beds 

 (22 ft. seen) near Abbotsbury (where they are quarried for build- 

 ing), which are on the same stratigraphical horizon and resemble 

 them in lithological character, scarcely contain a single fossil besides 

 My a cites, the only others noted being Pecten fihrosus and a Chem- 

 nitzia. 



At Weymouth this series has a less marked character, being split 

 up by marls and clays, and showing the oolitic structure less clearly, 

 shell-limestone being partially substituted. 



Here it consists, in descending order, of: — 



ft. in. 



1 . Blue marly clay, with oolite grains 6 6 



2. Small-grained sandy oolite, weathering hummocky, 



by its having shell-limestone substituted towards 



the base 2 



3. Marly clay with doggers 5 6 



4. Oolite, gritty in the centre and marly below, with 



Amm. perarmatus (var.) 6 



5. Blue sandy marls, partly argillaceous 4 



In the Ilodwell railway-cutting the oolite commences in abundant 

 grains in the underlying marls ; and at Wyke the whole oolitic series of 

 this and the beds above are united into one great false-bedded mass. 



The fossils of the Osmington Oolite are very interesting, partly 

 from their peculiarity as compared with those of the other beds of 

 the same district, partly from their similarity in facies to those of 

 the older beds which this series so strongly resembles in structure, and 

 partly from the assistance they afford in the correlation -of the series 

 with thoseof other districts, especially Yorkshire. They are as follows : 



