262 



Mr. Lonsdale on the Oolitic District of Bath. 



ally an undescribed, discoidal Ammonites. The sand and clay are almost 

 confined to the localities given in the preceding table*. 



2. The second division may be described as consisting of an earthy lime- 

 stone^ divisible into strata which do not preserve any definite arrangement, 

 and which pass insensibly into each other. The beds of Polyparia, to which 

 the division has been indebted for its name, sometimes occur near its top, 

 sometimes in its middle, and sometimes at its bottom. They are likewise of 

 limited extent. 



The accompanying diagram, drawn from Pinnel's Farm near Calne, to the 

 quarry on the north-east side of the brook at Quemmerford, will illustrate 

 the passage of the different varieties of the coral rag into each other. 



Lower greensand. 

 Kimmeridge day. 

 Rubbly oolite. 



Calcareous grit. 



The freestone, or " Oxford oolite," (2 a) occurs only at Calne. It is com- 

 posed of alternations of hard, shelly oolite, used for flags, and soft, earthy. 



* The sand is seen to the greatest advantage at Highworth, a town near the north-east angle of 

 Wiltshire : it is likewise visible about one mile from Lynham towards Wotton-Basset. The fol- 

 lowing section is from the Brick-kilns near Highworth. 



Top. Ft. In. 

 "Calcareous grit, in some parts oolitic : — thickness small. 



Rubbly oolite 1 



j Very fine sand, 1 foot to 3 feet 2 



[_ Sandy clay 3 



"Rotten oolite 2 



Oolitic clay 1 



Indistinctly oolitic limestone 1 



Friable oolite, with fragments of shells 



Indistinctly oolitic limestone 



Oolitic clay 



%{ 



Shelly, oolitic limestone I 



Rubbly oolite, containing numerous Caryophyllia 1 



Shelly, earthy limestone 1 



.Masses of blue, oolitic limestone, abounding with fragments of shells . 3 

 Calcareous grit. 



