QQ Rev. A. Sedgwick on the Geological Relations and 



Like most deposits of mere mechanical origin, the lower red sandstone is in 

 many places of so complex a structure, that a correct notion of it can only be 

 conveyed by a series of detailed sections. Considered on a great scale it is, 

 however, found to preserve a general uniformity of character, and may be 

 resolved into the following- principal varieties. 



1st. Conglomerate, resembling the newer red conglomerate which overlies 

 the western coal-districts. Of this variety there are some imperfect examples 

 at the upper surface of the sandstone near its junction with the magnesian 

 limestone ; but in such situations they may perhaps more properly be asso- 

 ciated with a superior division of the formation. (See Plate VI. figs. 1. 2. 3. 3.) 



2ndly. An extremely coarse siliceous sandstone, sometimes containing round 

 pieces of quartz more than an inch in diameter, which are generally ranged 

 in lines nearly parallel to the planes of stratification, though they are in other 

 respects very irregularly disseminated. This variety is so usually of a red or 

 purple tinge, that the colour may be regarded as characteristic of it. There 

 are, however, many local exceptions ; as the rock is in some places of a light 

 grey, and in others of a yellowish brown colour. It almost universally con- 

 tains a considerable portion of earthy felspar, which in some localities abounds 

 so much, that the whole rock becomes nearly incoherent. In these cases the 

 formation decomposes into irregular grotesque forms, and the face of the 

 country through which it passes is covered with rude concretionary blocks 

 which resemble decomposing boulders of granite or syenite. It is not possible 

 to mistake the nature of the earthy constituent; because crystals of red felspar, 

 sometimes exhibiting all their faces and angles, but most frequently rounded 

 or otherwise altered by attrition, are (in various stages of decomposition) 

 studded over the rugged surfaces of the sandstone blocks above mentioned. 

 At the same time it is extremely difficult to account for the abundance of this 

 mineral, as there are no granitic rocks near the range of the sandstone; and 

 the millstone grit and other beds of the contiguous coal-measures do not 

 appear to have contained felspar in such abundance as to supply the kaolin 

 and crystalline fragments which are imbedded in the superior formation. In 

 the places where the preceding variety predominates, the stratification is ge- 

 nerally obscure ; and there are constant examples of that kind of false bed- 

 ding in which the planes of separation of the principal masses are not parallel 

 to the planes of stratification. 



Srdly. A variety chiefly differing from the preceding in being smaller- 

 grained and more regularly bedded. Most of the beds are micaceous, and 

 some of them form a good stone, which is extensively quarried*. In this, as 



* In some parts of Yorkshire, especially between Wetherby and Knaresborough, these beds 



