G. H. Morton — The Bunter and Keuper near Liverpool. 499 



In the Bunter formation, the Lower Soft Sandstone is very 

 similar to the Upper Soft Sandstone in general appearance, but it 

 is coarser and the average size of the grains is larger than Tooth of 

 an inch in diameter. The chief distinction is the frequent occurrence 

 of large rounded grains from sVth to sVth of an inch in diameter in 

 a matrix of smaller ones, but they ai - e not always present and seem 

 peculiar to the subdivision in South-West Lancashire. Strata at 

 Croxteth, Tarbock and Kainford belonging to the Lower Soft Sand- 

 stone contain these large seed-like grains, embedded in a coarse- 

 grained matrix, but generally so loose that the rock has a soft sandy 

 character. At Knowsley the grains are held together by secondary 

 quartz and a quartzite of extreme hardness is the result. Kaolin is 

 always present and often some mica. 



The Lower and Upper Pebble-beds are formed of sandstone com- 

 posed of coarse rounded and subangular worn and crystallized grains 

 of quartz, associated with minute splintery fragments. Kaolin in 

 the form of grains and dust forms a conspicuous portion of the 

 rock. The typical sandstone of the Pebble-beds is almost a true 

 grit formed of angular grains, but the angularity is in consequence 

 of the crystallization of secondai'y quartz in planes and angles over 

 the exterior of the originally rounded grains in optical continuity. 1 

 The hardness and toughness of the Pebble-beds as a building-stone 

 is due to their compact and felted structure — the interstices between 

 the grains being tilled up with a fine dust of quartz and kaolin 

 and the whole cemented together by ferric-oxide and silica. The 

 grains of quartz are generally from TfVth to o^oth of an inch in 

 diameter, besides avast number of splintery fragments. In addition 

 to kaolin, mica and a few other minerals occur. 



The Upper Soft Sandstone is principally composed of small 

 rounded grains of quartz, varying from Toirfch down to minute 

 fragments Tooth of an inch in diameter. The structure is of a 

 loose sandy character, so that the sandstone soon disintegrates on 

 exposure to the weather. The highest beds are coarser than the 

 mass of the Upper Soft Sandstone, and occasional grains occur from 

 sV to tV of an inch in diameter as at Scarth Hill near Ormskirk, 

 Flaybrick Hill and Crown Street, Liverpool, but they are so rare 

 that they are not characteristic of the subdivision. Kaolin is always 

 present and usually a few flakes of mica. The finer grain of the 

 Upper, compared with the Lower Soft Sandstone, is well shown by 

 placing a series of specimens from each subdivision and from 

 different localities, together, when the average finer grain of the 

 latter is obvious. 



The Keuper Sandstone varies considerably in its microscopical 

 structure, and that near the base cannot be distinguished from that 

 of the Pebble-beds. The lower beds of the Keuper Sandstone are 

 composed of large, rounded, subangular grains of quartz, many of 

 which are covered with crystallized faces of a more recent origin. 

 Higher in the subdivision the sandstone is often formed of rounded 



1 The formation of crystals on grains of quartz in sandstoue was first described 

 by Prof. T. G. Bouney, F.E.S., in Q.J.G.S. vol. xxxv. p. 666. 



