Dr. Phillips on Estuary Strata in Shotover Hill. 75 



uprise of the coast-line, as having reference to the probably not yet 

 exhausted force of the volcanic foci of that region. 



November IS, 1S57. — Col. Portlock, R.E., President, in the Chair. 



The following communications were read : — • 



1. "On Estuary Strata in Shotover Hill, near Oxford." By 

 John Phillips, LL.D., F.R.S., F.G.S., Reader in Geology in the 

 University of Oxford. 



The author presented, in the first place, an historical notice of the 

 facts and opinions published in regard to the sandy strata which in 

 this detached hill rest upon the Portland series. From the time of 

 HoUoway (1722), to that of Smith (1800-1815), these deposits, 

 with their ochres and variously-coloured sands, were always classified 

 with the ferruginous sands, with ochre and fuller's earth, of Bedford- 

 shire and Buckinghamshire, and received the general title of " Iron 

 Sand." Conybeare (1822) uses the same title, traces tliem along 

 the vale of Aylesbury, and refers them to the Hastings Sands. At 

 this time, however, the Lower Greensand was not perfectly discri- 

 minated from the Hastings group. 



In 1827 Dr. Fitton appears to have ascertained the occurrence of 

 Purbeck deposits at Whitchurch in Buckinghamshire. About 1832 

 the Rev. H. Jelly discovered Paludiniform shells in the sands of 

 Shotover; and in 1833, and again in 1836, Mr. H. E. Strickland 

 communicated notices of this discovery to the Geological Society and 

 to Dr. Fitton, in whose great Memoir " On the Strata below the 

 Chalk" the information was published. From that time to the pre- 

 sent no further notice has appeared; but, previous to 1854, Mr, 

 Strickland, by his own researches, added a distinct U?iio to the shells 

 already collected ; and since 1854 the author of the present notice 

 has been enabled to augment the list of fossils, and to ascertain pre- 

 cisely the main facts regarding their geological position. 



The Portland rocks (70 feet thick), consisting of green sand, en- 

 closing one band of clay and two or three layers of large subcal- 

 careous concretions, are rich in fossils, and some of these (Pecien, 

 Perna, &c.) can be traced through the whole deposits to near the very 

 top. This group is suddenly covered by sands, white, yellow, brown, 

 reddish, or black, but not green ; banded somewhat regularly by 

 white or cream-coluured clays, and marked by imperfect ramifying 

 layers of deep-brown peroxide of iron ; chert-masses also occur. The 

 stratification, where most regular, as in the white sands and clays, is 

 often undulated, but there isverylittlc traceof obliqueordrift-bedding. 

 Ochre occurs in several parts of the section, and has been much 

 worked in the upi)cr ])art. The whole scries is about 80 feet thick. 



In all the lower half of the series, but only in the hard ferruginous 

 layers and geodic masses, and there not abundantly, we find conife- 

 rous wood, small sj)iral shells, and bivalve shells. The bivalves are 

 of the ;>enus Unio — one comi)iuable in size to Unto Valdensis, but 

 different in general figure, and in the ciiaracters about the fulcrum, 

 ligament, and posterior slope. The other is of smaller and more 



