416 PURBECK BEDS AND I RON -SAND. CHAP. 



iron-sands of Shotover, nearly to the top, were accumulated under 

 the influence of river-currents, which scattered the remains of fresh- 

 water organic life among them, we find this conclusion strengthened 

 by the facts, that at Combe Wood and Garsington, a little further 

 to the south of Shotover,, these sands were seen by Dr. Fitton to 

 cover a Purbeck deposit ' Malm/ with Paludina elongata and 

 another species, Planorbis (?), two species of Mytilus, Modiola, and 

 Cypris. Below is the Portland rock. 



' The section at Combe Wood consists of 



1. Reddish loamy soil, passing into 



2. Ferruginous sand (lower green). 



3. A thin bed of very tough clay (fuller's-earth ?) ; which with 2. enters into 

 and follows the deep erosions and irregularities at the top of 4. 



4. Purbeck. Stone and soft rubbly matter (the 'malm' of the pits at Gar- 

 sington), containing fresh-water shells like those of that" place : Cypris ; 

 Mytilus, two species; Modiola; Paludina elongata, and perhaps another 

 species? Planorbis? Some portions of the stone are compact and uniform, 

 with the usual characters of fresh-water limestone ; others, though containing 

 the same fossils, are composed of grey and brownish fine-grained oolite, in 

 which a very small univalve, perhaps a Paludina, occurs in such numbers as 

 in some places to form nearly the whole mass.' 



(Portland stone below.) 



At Garsington the following section was observed by Dr. 

 Fitton : 



ft. In. 



1. Loamy soil ........... 20 



2. a. Ferruginous brown sand, including portions like umber, and irre- ^ 



gular seams of clay (fuller's-earth?). It contains two patches of 



greenish sand 



&. A band of yellow ochre, about half an inch thick . . . ,' 



c. A thin bed of uniform tough clay (fuller's-earth) in wax -like j 



pieces, polished by motion under pressure J 



3. Malm, an agglomerate, composed of stone and softer marl-like matter -| 



much decomposed. 

 Among the components are 



a. Light greenish-grey marl, like some beds of the lowest chalk ; 

 containing at the upper part detached fragments of silicified coni- 

 ferous wood, like that of Portland, and portions of bone. 



6. Firmer pieces of stone, with some oolitic particles, including small 

 spiral univalves Paludina, perhaps of two species ? a Planorbis ? 

 Mytilus and Cypris. 



c. At the lower part the mass consists of larger pieces of uniform 

 limestone, in some places like the Pendle' of the pits at Whitchurch, 

 and including small Paludinse with other small spiral univalves, 

 Mytili and Cypris. Some of these pieces have a botryoidal, others 

 a finely oolitic, others a compact texture. 



(Portland stone below.) 



