Boulder-Clay. 



At Seaham ironworks and elsewhere, such sands and 

 gravels in the middle of the Till frequently thin away 

 in wedge-shaped ends. 



FIG. 83. 



I. Magnesian Limestone. 

 3. Sand and gravel. 



2. Lower Boulder-clay. 

 4. Upper Boulder-clay. 



It is unnecessary and would be wearisome to the 

 reader, were I to describe all the details of the sections 

 I have examined between Hartlepool near the mouth 

 of the Tees, and Spurn Point at the mouth of the 

 Humber. Suffice it to say that, in the Liassic and 

 Oolitic region of Yorkshire, the valleys that open upon 

 the sea are apt to be more or less filled with boulder-clays, 

 sands, and gravels, and the same phenomena occur in 

 many parts of the high sea-cliffs. Thus at Cromer Point, 

 about 2| miles north of Scarborough, there are beds 

 of sand and gravel in places about 120 feet thick, 

 which lie on an undulating surface of shales, &c., of the 

 Oolitic series. The embedded pebbles largely consist 

 of sandstones (Oolitic in part), grits, porphyry, &c., and 

 at the top, about 130 feet above the sea, there are beds 

 of clayey gravel with small stones and fragments of sea- 

 shells. 



In Cayton Bay, about three miles south of Scar- 

 borough, lying upon Oxford Clay, there is Boulder-clay, 

 with a great variety of boulders of Carboniferous Lime- 

 stone, Lammermuir grit, basalts, greenstones, and other 

 rocks that lie nearer the spot. Many of these are sub- 

 angular and many are well rounded, and both kinds are 



