Geological Society. 301 



March 7. — A Paper was read ". On the Geological Relations and 

 Internal Structure of the Magnesian Limestone, and the lower por- 

 tions of the New Red Sandstone series, in their range through Not- 

 tinghamshire, Derbyshire, Vorkshire, and Durham." — By the Rev. A. 

 Sedgwick, M.A. F.R.S. V.P.G.S. &c. 



A sketch of the subjects contained in this paper was laid before 

 the Society in 1826 (Nov. 17) : — They were resumed in a more sy- 

 stematic and detailed form during two meetings in 1827} and are 

 now terminated by the observations read at the present meeting. 



The contents of the Memoir are presented in the following order : 



Part I. — J 1 . Introduction. — The new red sandstone is considered 

 as one great complex formation, interposed between the coal measures 

 and the lias ; — with two calcareous formations subordinate to it, 

 one in the lower part of the series (the magnesian limestone), and 

 another in the upper part (the muschel-kalkstein) . The lower of the 

 two calcareous formations is considered in detail -, the upper has not 

 yet been discovered among the British secondary deposits. 



§ 2. External characters of the country through which the Magne- 

 sian Limestone ranges. — The form of the western escarpment is de- 

 scribed, and is supposed to exhibit proofs of great denudations j and 

 the general character of the soils resting upon the formation is no- 

 ticed. 



§ 3. General distribution of the formation. — The range of the es- 

 carpment is given in great detail ; some errors of the geological 

 maps are corrected; and in describing the eastern boundary, the 

 enormous masses of diluvium in the county of Durham are briefly 

 noticed. 



§ 4. Outliers. — Sixteen outliers from the western escarpment are 

 described ; the most southern of which is at Conisborough. In addi- 

 tion to these, there are eight detached patches of magnesian lime- 

 stone on the line of bearing, which are not considered as outliers. 

 The most remarkable of these are seen in the range through Yorkshire. 



§ 5. Relations of the Magnesian Limestone to a succession of Coal 

 Measures. — In a general point of view these formations must be 

 unconformable, because the overlying beds are extended far beyond 

 the limits of the productive parts of the carboniferous order : and 

 the fact is also proved by actual sections in several parts of York- 

 shire and Durham. At the same time there are continuous tracts of 

 country where the want of conformity does not appear, and where 

 the overlying beds seem almost to graduate into the coal measures. 

 Several details are given respecting ancient coal works, in which, in 

 more than one hundred places, the coal had been extracted by shafts 

 sunk through the magnesian limestone: and it is asserted that the 

 quality of the coal is never injured by the presence of the overlying 

 formations. Such injury is not only contrary to fact, but seems to 

 be a physical impossibility. 



§ 6. On the Faults affecting the Magnesian Limestone and Coal 

 strata, Trap dykes, #c. — Examples are given of some great faults 

 which traverse both the carboniferous and the superior formations : 

 but it is remarked that many of the dislocations of the lower order of 



rocks 



