C— GEOLOGY 



77 



Lake District erratics, and contain fragments of shells picked up from the 

 floor of the Irish Sea. In addition, there is material from Wales, but this 

 for the most part has probably been incorporated from the deposits of 

 earlier glaciations. There seems very little evidence of such older deposits 

 still in their original positions, though the Survey record Irish Sea drifts 

 at very different heights within a small area of the Trent valley south and 

 east of Stone, and again on and near Cannock Chase. At Wombourne 

 too, red boulder clay without Irish Sea material and with solifluxion 

 contortions may belong to an older series. 



Fig. 3. — Directions of ice-flow deduced from the distribution of Midland erratics, 

 i.e. excluding all far-travelled erratics. Cr., Croft Granophyre ; Mt. S., Mount 

 Sorrel Granite. In the south-west corner, i, 2, first and second stages of the 

 First Welsh maximum ; 3, the Woolridge Terrace rivers of Leadon and 

 Severn valleys. 



The Irish Sea glacier advanced inland counter to the drainage, and in 

 our district surmounted the watershed and spread a short distance down 

 the valleys of the Severn, Worfe, and Smestow on the south, and entered 

 the valleys draining eastwards to the Tame and even advanced some way 

 down the Main Trent valley (Fig. 2). Its drifts reach to 800 CD. at 

 Castle Ring on the east side of Cannock Chase. 



