300 J. F. BLAKE AND W. H. HUDLESTON ON 



is due chiefly to the shape of its supporting rocks. There is a con- 

 siderable descent over sands and grits below any thing seen in the 

 quarries before the springs indicate the Oxford Clay, the Survey esti- 

 mate being 80 feet. 



As we depart on either side from this line we find the beds much 

 diminished, especially on the west, where the great sandbank and its 

 supported limestones take their origin. We see just the beginning of 

 it, as it were, in an opening near the turnpike, on the western road, 

 like the little miniature formation at Green's Cleeve, near Clack. 



Section at HigJiiuorth Turnpike. 



ft. in. 



1. Blue, fissile, large-grained, rough but not oolitic 



limestone, with Ammonites plicatilis and Echino- 

 brissics scutatus 8 in. to 1 



2. Soft brash, with shell-fragments, and a 4-inch 



rubbly limestone, with A. plicatilis near the top... 1 2 



3. Coral-bed, with all the corals (Thecosmilice) lying 



down flat, with Littorina muricata, Lima elliptica, 

 Pecten jibrosus, Exogyra nana, and Echinobrissus 

 scutatus 1 



4. Light-coloured limestone, weathering brasoy, con- 



taining Ammonites cordatus, Sowerbya triangu- 

 laris, Pecten jibrosus, Ostrea solitaria, and a great 

 number of casts of Cyprina tancrediformis, 1 ft. to 1 6 



5. Calcareous sandstone 3 



6. Sand and sandstone 3 3 



The occurrence of the Coral-bed here enables us to correlate this 

 section with that of the south quarry, and to see, as pointed out, the 

 greatly diminished thickness of the beds, while they maintain an 

 almost exact correspondence. 



A similar section in a quarry on the east side of the town proves 

 the falling-off to be less in that direction. 



Section in the East Quarry, Highworth. 



ft. in. 



1. Brown clay, slightly laminated 2 6 



2. Brashy oolite 1 8 



3. Grey shelly limestone, slightly oolitic, in two 



courses, parted by brash 2 8 



4. Hard limestone, with ball-concretions and Theco- 



smilice 2 4 



The Coral-bed is here scarcely discernible ; it is probably at the 

 top of No. 4, in which case the correlation is clear. Bed No. 3 

 is as fossiliferous as the corresponding one in the south quarry 

 (4 of the type section), and adds the following fossils to the list 

 (their tendency being certainly to assign it to the age we have in- 

 dicated) viz. : — 



Trigonia Meriani (Ag.). 

 Modiola cancellata (Rom.). 

 Avicula expansa ? (Ph.). 



Hinnites velatus (Gold/.). 

 Trichites Plotii (Lhwyd.). 



