582 ME. P. G. H. BOSWELL OK" THE [Dec. I9I3, 



stream of any size in Suffolk flowing north-westwards into the 

 "Wash basin (see map, PI. LIV). 



The western part of the county lies within the area of the Chalk 

 outcrop ; but, as we travel eastwards, this formation is seen to 

 dip at about 15 feet to the mile, and is successively overlain by 

 Eocene beds (Thanet Clays & Sands, Woolwich & Beading Beds,. 

 Oldhaven Beds ?, and London Clay) and by the East Anglian Crags- 

 (Red and Coralline Crag in the south, Norwich Crag and Chillesford 

 Crag, etc. in the north). However, the whole country is more 

 or less plastered over with a thick mantle of Glacial Drift, and 

 therefore the so-called ' solid geology ' is revealed only in the 

 deeper and more important valleys. 



The Drift consists of : — (a) The Lower Boulder Clay (that is, 

 the Contorted Drift or Norwich brickearth), continuous with 

 that deposit in Norfolk, occurring in the northern part of the 

 county only. 



(b) The series of beds of sand, gravel, and loam (brickearth), 

 which underlie the Upper Boulder Clay (c), and were conveniently 

 grouped with other gravels of different. ages by the Geological Survey 

 under the general term 'Middle Glacial' of S. V.Wood, Jun. 

 The gravels are usually ' clean ' (that is, not loamy or much iron- 

 stained), horizontally or current-bedded, and show marked selective 

 deposition in the matter of the size of their constituent pebbles. 

 The term ' shingle ' is frequently applied to them in well-borings. 

 They are largely composed of much altered and waterworn, opaque, 

 red and brown flint, together with vein-quartz, sandstones, and 

 quartzite (Bunter pebbles and sarsens) ; also, less commonly, 

 Jurassic debris and igneous or metamorphic rocks. The sands are 

 sharp, clean, quartzose, and often highly current-bedded. They 

 are white, yellow, pale brown, or red, and generally coarse, the 

 last feature usually serving to distinguish them from the Beading 

 Sands that occur in the area. The loams or brickearths are, as a 

 rule, buff or blue, and are very homogeneous and finely laminated. 

 Less commonly they contain big flints and Jurassic fossils and 

 boulders. Experiments have shown that precisely similar material 

 has resulted from washing the Upper Chalky Boulder Clay free 

 of rock-fragments and allowing the sediment to settle. Indeed, 

 this process is carried out in several brickfields to obtain a pure 

 ' earth ' from the Boulder Clay for the manufacture of white bricks- 

 The loams are thus clearly outwashed from the Upper Boulder 

 Clay, and they occur in lake-like patches scattered over the county. 



(c) The Upper Boulder Clay, part of the Great Chalky Boulder 

 Clay of S. V.Wood, Jun., which covers East Anglia and the Midlands. 

 Mr. Harmer has recognized two distinct types in Suffolk : the 

 Chalky Boulder Clay of the western and south-western portions ;• 

 and the Chalky- Kim eridgic Boulder Clay which forms the high laud 

 of Suffolk, and covers the east and south-east of the eountj'. 



(d) A series of gravels that lie above the Upper Boulder Clay, 

 and are referred to in this paper, for the purpose of distinction ,. 



