1909-1910.] iq-j 



representatives of the same system of rocks as are to be found on 

 the Dorset coast. There is, however, a remarkable gap, indicating 

 either a break in the Jurassic sea connection or the complete 

 denudation of the whole upper Jurassic series from County 

 Antrim. In a traverse from, say, the east end of Fortwilliam 

 Park to the top of the Cave Hill chalk quarry we pass over the 

 following upward succession : — Triassic sandstone and Keuper 

 marls, rhsetic shales, lower lias, greensand, chalk, the two last- 

 mentioned belonging to the Cretaceous system. A similar traverse 

 on the Dorset coast from Lyme Regis to Swanage supplies us 

 with the following links in the chain of succession between the 

 lower lias and the greensand. Taking them in ascending order, 

 we have middle lias, upper lias, oolite, middle oolite, upper 

 oolite, wealden. Again, each of the oolitic divisions is 

 separable into distinct formations. Some of these separate 

 formations of the oolitic series are of great thickness, and all are 

 of an interesting character. In the series we have two great clay 

 formations — the Oxford and the Kimmeridge clay. The other 

 formations with which these clays are associated are mostly 

 calcareous sands and limestones, the corallian and the Portland 

 series of rocks being the most decidedly dominant in type and 

 importance. 



The lecturer then proceeded to give a detailed exposition of 

 the succession of strata exhibited on the coast-line from Lyme 

 Regis to Durlstone Head and Swanage. Nowhere in the country 

 is the great liassic formation so admirably represented as between 

 Lyme and Eridport. The general dip of the beds is to the east, 

 so that a traverse of the coast brings the observer into contact 

 with the successive divisions of the series, as the younger and 

 higher beds are successively brought down to sea-level owing to 

 the regular dip of the rocks. Between Bridport and Weymouth 

 the lower, middle, and upper oolites are well developed. From 

 Abbotsbury to Osmington, on the north side of Weymouth Bay, 

 fine sections in all these strata can be examined. The great 



