496 Geological Sociefj/. 



of the system consiilere3 by the author as undescribed is a conglo- 

 merate, 1 00 feet thick, which occurs at the Park at Ugbrook. It is com- 

 posed of rounded quartz pebbles and fragments of clay slate, united 

 by a siliceous cement. It alternates in the upper part with beds of 

 ciay slate, and is older than any of the limestonesof the country. These 

 transition formations are traversed by numerous faults, the strata being 

 thrown into the wildest confusion. In some places beds of trap are 

 regularly interposed without producing any effect upon the adjacent 

 strata ; but in other localities dykes intersect the sedimentary deposits, 

 and have produced great alterations both in their structure and dip. 



The new red sandstone consists in the lower part of fine-grained fissile 

 sandstone, and a coarse conglomerate, formed out of the surround- 

 ing older formations, including partially rounded fragments of slate, 

 limestone, porphyry, greenstone, &c. This formation is also much 

 disturbed by faults, some of which, the author thinks, are contempo- 

 raneous with the deposition of the sandstone, as they appear to affect 

 the lower and not the upper beds in the same section. 



The elevation of the greensand of the Haldons, Mr. Austen thinks, 

 was due to the action of a subjacent mass of trap, portions of which 

 are visible at the extremities of the hills: and he is of opinion that the 

 preservation of these insulated patches of greenstone has been owing 

 to their having been raised above the level of the waters which denu- 

 dated the surrounding districts. 



In conclusion the author briefly reviews the geological phenomena 

 which this part of Devonshire presents, and infers from them, that du- 

 ring the transition epoch there were submarine volcanic irruptions, as 

 shown by the interstratified trap ; that the number of organic remains 

 in the limestone prove that the ocean teemed, in parts, with life : that 

 the new reJ conglomerate was due to the breaking up of the transition 

 formations : that there were irruptions of trap at later periods, as proved 

 by the dykes in the new red sandstone; and that Dartmoor was ele- 

 vated after the deposition of the greensand, as the first traces of gra- 

 nitic debris are found in the Bovey deposit. 



A notice was next read on the supposed existence of the Lias forma- 

 tion in Africa, by Roderick Impey Murchison, Esq., F.G.S. 



Mr. Leach, of Milford Haven, a short time since presented to the 

 Society some organic remains, stated to have been obtained by Com- 

 modore Sir Charles Bullen on the west coast of Africa. As these or- 

 ganic remains agree exactly with fossils of common occurrence at Lyme 

 Regis, it was conjectured that some mistake might have occurred re- 

 specting them ; but Mr. Leach has been subsequently informed by 

 Sir Charles Bullen that they were collected by himself and officers at 

 West Bay, Fernando Po, Accra, andSierra Leone, and that they occur 

 in abundance. 



Mr. Murchison also announced in this notice, that Sir John Herschel 

 has discovered Trilobiles in a rock which occurs to the north of the 

 Cape of Good Hope. 



A paper was then read, entitled " A Notice on Maria Island, on the 

 east coast of Van Diemen's Land, (S. lat. 42° 44' E., long. 148° 8',) 

 by George Frankland, Esq., Surveyor-General of the Colony; and 



