8o 



SECTIONAL ADDRESSES 



(Fig. 4) gives an indication of where these few wanderers have been met 

 with. We may perhaps infer from their distribution that they belong to 

 a later stage in the glaciation than that which was responsible for the more 

 southerly Welsh Drifts, these being devoid of the Northern elements. 

 It is important to realise that various lines of evidence point to the fact 

 that it was not the Main Irish Sea Glacier, but an earlier one that intro- 

 duced these few boulders. 



..'X- 



l.'^-" 



- ScoIa of MtUs - 



Fig. 4. — Distribution of Drifts : — 



(i) Welsh Re-advance maximum ; (2) Main Irish Sea maximum ; (3) Welsh 

 maximum ; (4) Older Drifts, Welsh and local ; (5) Older Drifts with Pennine 

 boulders ; (6) Irish Sea boulders (rare) in older drifts. Those in the Salwarpe 

 valley may be water-borne ; those in the Main and Worcester Terraces are 

 omitted ; (7) Very ancient boulder clay with north-eastern erratics and 

 overlain by ? Interglacial sands and gravels ; (8) Interglacial gravels, ' Jurassic 

 gravels ' and ' Ditchford gravels.' 



The deposits of the Great Eastern glacier omitted. 



Owing to its position between the spheres of influence of the Irish Sea 

 and the Great Eastern glaciers this central area with predominantly 

 Welsh drifts offers borderline cases where it is difficult to decide to 

 which glaciation a particular deposit belongs. The Kingswinford Esker 

 described by Boulton, and the gravels with many northern boulders at 



