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



of each subdivision of the Bunter and Keuper derived from railway 

 cuttings and tunnels, borings for water and coal-pits. 



Feet. 



, it om i i ( Red Marl 400 



Keuper, 800 feet { Keuper Sandstone _ 400 



Tkias < I Upper Soft Sandstone ... 550 



f t> j. ,nt n ( ,) Upper Pebble-beds ... 400 



I Bunter, 1950 feet j L ^ erPebblebeds _ 6QQ 



[ Lower Soft Sandstone ... 400 



2750 

 The whole thickness in 1863 was supposed to be about 1700 feet, 

 and was obtained from the measurement of outcrops of the strata, 

 but it is now proved to be 2750 feet. The Ked Marl at the top of 

 the Keuper, and the Lower Soft Sandstone at the bottom of the 

 Bunter, however, vary in thickness from a few to 400 feet. 



Microscopic Structure. 



In each of the subdivisions of the Trias the sandstones present 

 a typical character, though it often happens that some interstratified 

 beds of a softer or harder nature occur and differ from those 

 forming the rest of the strata. A few specimens from any sub- 

 division will often indicate the horizon to which they belong, but 

 it must not be supposed that a single piece of the sandstone is 

 sufficient for the purpose. 



In a series of beds of sandstone 2350 feet in thickness, excluding 

 the Red Marl, and which vary on the same horizon in different 

 localities, it is difficult to draw general conclusions of much value 

 The microscopic examination, however, of a great number of 

 specimens from many horizons in the Trias about Liverpool shows 

 that there are five normal types, although they run, more or less, 

 into each other. 



Firstly — Coarse-grained sandstone, composed of rounded and 

 subangular grains of quartz, larger than Tooth of an inch in 

 diametei*. 



Secondly — Fine-grained sandstone, composed of rounded and 

 subangular grains of quartz smaller than T o~oth of an inch in 

 diameter. 



Thirdly — Coarse-grained sandstone, containing a great number of 

 large grains of quartz aVth to - 3 Vth of an inch in diameter, like a 

 minute conglomerate. 



Fourthly — Coarse-grained sandstone, composed of rounded, sub- 

 angular and crystallized grains of quartz — the crystallized faces 

 having been deposited on the original grains after the sandstone 

 was formed. 



Fifthly — Coarse-grained sandstone, or quartzite, originally formed 

 of rounded and subangular grains which have been united by the 

 deposition of silica into a hard rock after the formation of the 

 sandstone. 



All these sandstones contain, in addition to the grains described, 

 a great number of small splintery fragments of quartz down to 

 ToVoth of an inch in diameter and so fine as to resemble dust. 



