364 GEOLOGY OF THE ISLE OF PURBECK. 



contain ammonites, trigoniae, and the usual Port- 

 land shells, and veins and nodular masses of chert. 

 A bed of oyster shells, which an infiltration of 

 calcareous matter has converted into a hard shelly 

 conglomerate, like that of Bromley, in Kent,* 

 occurs in the upper part of the series. The 

 quarries at Tillywhim are generally visited by 

 parties in the summer, on account of the romantic 

 character of the scenery, and the delicious cool 

 retreat afforded by the caverns or excavations ; 

 these are reached by a path that winds through 

 a deep valley, strewn with masses of stone, 

 and the descent is by steps cut in the rock.-j- To 

 the eastward there are similar caves, formed by 

 the extraction of the layers of limestone : fine 

 specimens of the oyster-shell conglomerate may 

 be obtained from near the summit of the cliffs. 



Lofty perpendicular cliffs of oolite, capped 

 with Purbeck strata, continue along the coast to 

 the west; and at the distance of about three miles 

 from Tillywhim, the Portland stone is worked in 

 Windspit quarries,! which are excavations in the 

 cliff, like those at the former place. 



About a mile to the west of Windspit quarries, 



* See Medals of Creation, vol. i. p. 385. 



t A view of the cliff at Tillywhim is given by Mr. Webster, in Sir II 

 Bnglefield's Me of Wight, pi. xxxiii. 



■ <i in pi, xxxii. of tin- same- work. 



