OF THE NORTH-WEST OF ENGLAND. 221 



such clays being filled with lower new red sandstone. There 

 was no trace here of the passage of the carboniferous into the 

 permian strata, and the two are, without doubt, quite un- 

 conformable to each other in this locality. 



In the turn of the river Medlock, below Mr. Schofield's 

 chapel, the upper new red sandstone has not been seen in 

 absolute contact with the carboniferous strata, but it was 

 traced to within less than one hundred yards of them. They 

 here consist of red and greenish mottled clays, containing a 

 bivalve shell,* and parted by thin bands of gritstone. These 

 last-named strata are succeeded by argillaceous and arenaceous 

 beds of red and variegated colours, containing the limestones 

 and thin coals of Ardwick, which are followed by the coal- 

 measures of Bradford and Clayton, comprising the whole of 

 the known part of the upper and the higher part of the middle 

 division of the Lancashire coal-fields, reaching altogether to 

 about 3,000 feet in vertical thickness, and dipping nearly 

 south-west at angles varying from 18 to 25°. At Bank Bridge, 

 a little to the south of Mr. Wood's print works, the carboni- 

 ferous strata are thrown down t by a fault of very great, but, 

 as yet, unknown depth, but certainly above 3,000 feet, run- 

 ning from north to south, and covered by upper new red 

 sandstone for a distance of about two miles. All the way 

 from Mr. Wood's to beyond Clayton Bridge, the upper new 

 red sandstone has been proved ; and in that gentleman's estate. 



• This shell Professor W. C. Williamson, F.R.S., in a paper published in the 

 Phil. Mag., for Nov. 1830, p. 241, called Unio Phiilipsii, in its compressed 

 state, but to me it appears, when uncompressed, more like a Modiola than 

 an Unio. 



f This fault is generally termed a down throw, but it is very difficult to 

 prove whether it is down or up, for the edges of the carboniferous strata have 

 been so washed and eroded by the action of the waters in which the permian 

 and trias beds were deposited, as to remove all chance of determining the direc- 

 tion of the fault by the usual means. 



