42 Rev. A. Sedgwick on the Geological Relations and 



A formation^ which in some places stretches in a continuous terrace through 

 a finely diversified country, and in other places is broken into outliers and 

 modified by denuding forces, must necessarily give rise to many scenes of 

 great variety and beauty*. But, on reaching the top of the terrace and cross- 

 ing the back of the formation, the country (except where it is cut through by 

 valleys of denudation, or covered by accumulations of diluvial matter,) is 

 seldom found to exhibit any great diversity of surface; and most frequently 

 forms an extended plain gradually declining towards the east. The newest 

 portion of the deposit in some parts of Nottinghamshire and Yorkshire forms 

 a second terrace, the beds of which dip like the former, and gradually sink 

 below the level of the great plain of the new red sandstone ; most frequently 

 without an escarpment, or any other geological feature to mark the line of 

 junction. 



The agricultural character of the country in which the magnesian limestone 

 prevails is various ; partly from the changes of the formation, and perhaps still 

 more from the accumulations of extraneous matter between the soil and the 

 rock. It may, however, be observed, that when the soil rests immediately upon 

 the rock, it is generally rather light and unproductive, and never exhibits that 

 beautiful green vegetation which abounds in many limestone countries. 



Its colours in Nottinghamshire are sometimes red or chocolate brown ; and 

 hence the name red-land limestone, given by Mr. Smith to the magnesian 

 beds. These appearances are, however, the exception ; for a red soil derived 

 from the limestone is hardly seen in the other counties : the prevailing colours 

 are lighter, and generally have the yellow tinge of the accompanying dolo- 

 mitic strata. 



Brotnus pinnatus is so characteristic of the thin and magnesian soils, 

 that in some instances where the lower sandstone is brought by a fault to the 

 exact level of the yellow limestone (for example on Bramham Moor), the de- 

 marcation may be traced with great exactness by the help of this plant, without 

 the assistance of a single excavation. 



§ 3, Range of the Escarpment, and general Distribution of the Formation. 

 So far I have endeavoured in general terms to explain the great relations 



* The outliers and the escarpment of the magnesian limestone have at different times been 

 adorned with many noble buildings, some of which acquired a great historical interest. For ex- 

 ample, Conisburgh Castle, Pontefract Castle, Tynemouth Abbey and Castle, rest upon outliers 

 of the magnesian limestone ; llardwiclc Hall, Bolsover Castle, Knaresborough Castle, and Hilton 

 Castle, stand close upon the edge of its escarpment. Other examples of the same kind might be 

 mentioned if this were the proper place for entering on such details. 



