Vorks/iiiT Ghu/'ci'-Ltikcs. 15 



Glacial Period. Three main ice-masses appear to have been 

 concerned in producing' the deposits : one from the Southern 

 Uplands of Scotland and the Solway, joined by the local ice o'i 

 the Tees; a second originating" in the Tweed Valley, and driven 

 southward round the Cheviots by the pressure of the third, 

 or Scandinavian, ice-mass. The general order of events is 

 supposed to have been (i) the unobstructed passage of the 

 Teesdale glacier to the coast ; (2) the arrival of tlie Scandinavian 

 ice ; and (3) the invasion of the Scottish ice. 



I;ll_r Beck and Fen Bogs. 



The first of the extra-morainic lakes described is that oi the 

 \'ale of Pickering, the lowest of the sequence, which for a long- 

 period received all the drainage of the district except that of the 

 western margin, and the outflow from which into Lake Humber 

 is now occupied by the River Derwent. Xewton Dale was 

 the outflow oi the lake-series of the Eskdale country. The 

 Eskdale system comprises a series of lakes connected by an 

 ' aligned sequence ' of overflows, and here it is possible to trace 

 the consequences of the shrinkage of the ice-masses, and to 

 follow out the low-level phases of the lake. The ice pressing 

 upon the northern face 0*1 the Cleveland Hills gave rise to 



1903 January 3. 



