179 



coiitriliuted by Prof. Sollas to Section C. of the British 

 Association in 1900, shows hoM' this thickness is made np by 

 the various formations : — 



Feet. 

 Recent and Pleistocene ... ... 4,000 



PKocene 5,000 



Miocene 9,000 



Oligocene 12,000 



Eocene 12,000 



Cretaceous 14,000 



Jurassic ... ... ... ... 8,000 



Trias 13,000 



Permian 12,000 



Carboniferous 24,000 



Devonian 22,000 



Silurian 15,000 



Ordoviciau 17,000 



Cambrian 16,000 



Keweenawan ... ... ... 50,000 



Penokee 14,000 



Huronian 18,000 



In our district we are not concerned witli tlie older formations. 

 At Middlesbrough we bore down to the Trias for salt, and this 

 formation is found in other places at the surface, but as to what 

 is below it we can only speculate, though in all probability the- 

 Permian and Carboniferous would be foiuid if we could jiut down 

 borings deep enough. 



We look across to the Pennines, and find the axis to b& 

 composed of Carboniferous rocks, consisting of the Carboniferous 

 Limestone and Yoredale Beds overlaid by the Millstone Grit. 

 Probably the Coal Measures were originally more or less continuous 

 over these, but, being on the whole easily denuded, they have 

 disappeared, while the hard Millstone Grit has survived the wear 

 and tear of Nature's disintegrating forces, and protectively caps 

 most of the higher ground. Lying unconformably on the flanks 

 of the Carboniferous strata, the rocks of the Permian formation 

 extend north and south in a band about five miles Avide with a dip 

 to the E.S.E. 



The valley between the Cleveland Hills and this Permian 

 band is mainly occupied Ity the soft sandstones and marls of the 

 Trias, though, owing to the thick deposit of Glacial Drift, they 

 are seldom to be seen They dij) to the east, passing under the 

 rocks of the Jurassic svstem. 



