GeologT/ of the Neighbourhood of Weymouth, S^c. 31 



careo-slliceous sandstone, and in the lower region interrupted strata of large 

 concretions of coarse sandstone ; the lowest strata of this formation become 

 gradually more blue and marly, and at length pass insensibly into the upper 

 marl beds of the lias. 



We observed a remarkable fact in some stony masses from the middle 

 region of the inferior oolite at Down Cliff on the west of Bridport, namely, 

 that some of these masses contained an oolitic breccia or conglomerate of 

 rolled fragments of coarse oolite, not differing in character from the strata of 

 which they form a part. The fragments in this breccia are not concretions, 

 but afford unequivocal evidence of having been rolled by water, in the fact 

 that many of them are perforated on all sides by the holes of small Lithodomi, 

 of which holes the lower extremities alone remain, their tops having been 

 worn away by the attrition which has reduced the fragments in which they 

 occur to the state of large subangular pebbles ; these fragments must have 

 Iain loose in the sea at the time when the Lithodomi perforated their surface, 

 for one side only could have been perforated before they were detached from 

 their native rock ; and the perforation of the lower side at least, if not of the 

 other sides, must have taken place in a period intermediate between such 

 separation and the completion of that moderate degree of rounding which 

 they have since undergone. We see at this time on the ledges of the shore 

 at Lyme, between high and low water mark, loose angular slabs of lias 

 recently torn from the subjacent strata, and perforated on all sides by boring 

 Molluscse, after the manner of the fragments in our oolitic breccia. This 

 perforated breccia at Down Cliff shows a lapse of time to have intervened, in 

 which there was apparently a suspension of the deposition of the inferior 

 oolite; a time in which fragments were torn by the waters from the earlier 

 beds and became inhabited by Lithodomi, and subsequently rolled on the 

 shores, or at the bottom of the then existing seas ; they further show that the 

 lower strata of the inferior oolite were at once consolidated to the condition 

 of stone, hard enough to protect Lithodomi and to be rolled to pebbles, before 

 the upper strata of this same inferior oolite formation had been laid over them. 



Lias. 



The western extremity of our Map includes the upper marl beds only of the 

 lias formation ; these are exposed at the bottom of the valleys of denudation 

 round Golden Cap Hill, and on the sea-shore along its base : they are cha- 

 racterized by enormous deposits of Belemnites, and correspond with the Cal- 

 caire a Belemnile of the French geologists, as the lower and more stony beds 

 of lias at liyme agree with the French Calcaire a Gryphite. One bed at the 



