A. Strahan — Lower Kevper Sancktone. 



397 



VERTICAL SECTION OF A PART OF 

 THE TRIAS NEAR CHESTER. 

 Scale 500 feet = i inch. 



f 



<a o 



M ft 



L - 



I Keuper Marls 

 J (part of). 



T 



I Waterstones. 



I 

 J 



Lower Keuper 

 I Sandstone or 

 y Basement Beds. 



■y' 



From the description of tlie Frodsham Beds given above, it will 

 be seen that they are similar in character to the Upper and Lower 

 Mottled Sandstones of the Bunter. Indeed even in the field they 

 cannot be distinguished from these subdivisions except by ascertain- 

 ing their relative position to the conglomerates of the Keuper Base- 

 ment Beds below and the Waterstones above. 



After the deposition of the Frod- 

 sham Beds, a complete change must 

 have taken place, for the Waterstones 

 which succeed them are of an en- 

 tirely different lithological chai'acter, 

 and belong to the Keuper Marl type 

 exclusively. They consist of evenly- 

 bedded or laminated, loamy, and 

 micaceous sandstones, alternating 

 with shales, the whole presenting an 

 appeai'ance of extreme regularity of 

 bedding, suggestive of deposition 

 in tranquil water. The peculiar 

 loamy texture and the absence of 

 the conglomeratic character in these 

 sandstones renders them easily dis- 

 tinguishable from the building 

 stones of the Lower Keuper Sand- 

 stone, even after removal from the 

 quarry. 



The contrast between these two 

 subdivisions and the sharpness of 

 the line dividing them is beautifully 

 shown in the railway cutting at 

 Euncorn Station. The lowest beds 

 of the Waterstones consist of deep 

 red shales and micaceous flags, and 

 rest directly upon the loose current- 

 bedded sand of the Frodsham Beds. 

 At the south end of the cutting the 

 Frodsham Beds are red, but at the 

 north end white, the loss of colour 

 taking place gradually in passing 

 from one end of the section to the 

 other. The same junction is ex- 

 posed in the road leading from 

 Frodsham to Overton, and in a 

 lane near Overton Church (Geology 

 of the Country around Prescot, 

 fig. 5), on Eddisbury Hill, and in 

 Delamere Forest. Even where good 

 sections are wanting, the line can be 

 followed with ease by the change in the soil, resulting from the 

 juxtaposition of rocks so different in character. 



VI: 



'/oyc 



Lines of Erosion. 



Erosion. 



Upper Mottled 

 Sandstone. 



I Erosion. 



Pebble Beds. 



Erosion. 



Erosion. 



Lower Mottled 

 Sandstone. 



