CHAPTER II. 



OOLITIC SYSTEM. 



Inferior Oolite. — Lias. — Outliers of Lias. 



ORIGINALLY I had no intention of describing any rocks of so recent an age as 

 the Oolite and Lias. The work was to have commenced with an account of the 

 New Red Sandstone, as the youngest secondary deposit in the vicinity of any portion 

 of the" Silurian System." The discovery, however, of a great outlier of Lias in the 

 North of Shropshire and adjacent part of Cheshire, where the existence of that forma- 

 tion had never been even suspected, has induced me to extend the plan, and to preface 

 an account of that large insulated mass, by a few observations on the relations and 

 .structure of the Inferior Oolite of the Cotteswold Hills, and of the Lias of the Vale of 

 Worcester and Gloucester ; more particularly with the view of showing how the latter 

 passes down into the New Red Sandstone 1 . 



In general terms, the Oolitic Series maybe described as a great and diversified group 

 of limestones, sandstones, grits, and clays, ranging across our island from Dorset- 

 shire on the south-west to Yorkshire on the north-east. The central members of this 

 group occupy the high districts of Oxfordshire and Gloucestershire, which form the 

 eastern limits of the annexed map. In this district Mr. Lonsdale has worked out with 

 great assiduity the relative position of the different members of the system, rectifying 

 an important error in their classification, and laying down their outlines to a great 

 extent on the maps of the Ordnance Survey 2 . 



1 Smith's Strata Identified. It was in the oolitic series of the adjacent counties, that Smith established the 

 great principle of identifying the English strata by their imbedded organic remains. For information respecting 

 the Oolitic Series, see Outlines of the Geology of England and Wales, by Conybeare and W. Phillips ; Geology 

 of Yorkshire, 1st Vol., by Professor Phillips. Also various Memoirs in the Transactions of the Geological 

 Society of London, by Messrs. Buekland, De la Beche, Lonsdale, and Murchison. 



? In pursuing his examination of the range of the Oolites, Mr. Lonsdale was the first to discover the true 

 geological position of the Stonesfield Slates, so long known to collectors by the beauty and number of their 

 organic remains. These Tilestones were formerly supposed to overlie the Great or Bath Oolite, but Mr. 

 Lonsdale has shown that in the Cotteswold Pvange they form the bottom of that rock. Having myself ex- 

 amined a portion of this district in detail, I may be allowed to state my belief that no geologist could so clearly 

 and systematically have rectified this important error of previous observers in the order of these beds, as Mr. 

 Lonsdale ; for no one had so closely studied their relations in the Bath district, whence as a type or base he 

 extended his inquiries. 



B 



