106 T. M. KEADE Otf THE DKIFT-BEDS OF THE 



The surface of the sands he describes as " extremely undulating, 

 often causing the Upper Boulder-clay to come in somewhab unex- 

 pectedly," p. 17. The long winding bluff forming the north 

 margin of the Eibble valley, between Preston and Eedscar, exhibits 

 very fine sections of the " Middle Sands." Mr. De Ranee describes 

 many other sections ; but they all consist in this valley of Middle 

 Drift and Upper Boulder-clay, the former being in the greatest 

 force ; and he states that the four largest towns of the district 

 are built on Middle Drift, viz. Preston, Kirkham, Chorley, and 

 Leyland. 



Remarks. 



The sections described in this basin are extremely instructive. 

 If we begin and retrace the drift down the Eibble valley from 

 Moughton in Ribblesdale, we find it first composed almost entirely 

 of local materials, the limestone vastly predominating and providing 

 not only the boulders but most of the materials for the matrix ; as 

 we descend this drift gets more and more mixed with Carboniferous 

 sandstones and grits from the Pendle Hills and the tributary Calder, 

 especially in the upper beds. The underlying blue Till still con- 

 tains a preponderance of limestone rocks ; but by far the most 

 remarkable fact is that this Till has been forced up the gorge 

 of the Calder against its drainage, as already described. As we 

 near Ribchester the true low-level marine clays come in, over- 

 lapping the more local drift of the Ribble valley. Below Rib- 

 chester the drift becomes all marine, the yellow shelly sands being 

 highly developed. The Triassic and Carboniferous sandstones have 

 yielded the materials for these sands ; and the red shelly Boulder-clay 

 has been laid down upon it, apparently from a sea-drift. It is also 

 a noticeable fact that the included granitic boulders and the true 

 sea- drift stones from the Lake district so plentifully found in all 

 Low-level Boulder-clays and sands almost, if not entirely, cease above 

 Mitton Bridge. 



Deift of the Coast fkom Blackpool to St. Bees. 



At Blackpool there is a well-known section of Drift exposed in 

 the sea-cliff. It was described by the late Mr. Binney, F.R.S., in 

 1852, in the Memoirs of the Literary and Philosophical Society of 

 Manchester, and since by many other geologists. 



Mr. De Ranee especially has paid much attention to it. In 

 August 1872 I made a very careful section of it from Bispham to 

 Gynn, a distance of about 3600 yards, or just over 2 miles (fig. 25). 



Commencing at the furthest point from Blackpool, viz. Bispham, 

 and working south, the beds run in the following order : — Pirst, 

 there is a red Boulder- clay, A, not very stony, which a little 

 further on has intercalated in it towards the top two thin bands of 

 stratified sand, B ; these curving downwards join two remarkably 



