Yol. 69.] AGE OP THE SUFFOLK VALLEYS. 591 



(b) Opposite to Gallows Hill, on the left bank, the small 

 tributary stream known as the Coddenham Brook joins the main 

 river. The result of this is to produce a strong bluff (Beacon 

 Hill) at the northern end of Shrubland Park, pointing, as it were, 

 up the valley, on account of the angle at which the tributary 

 valley comes in. The high road cuts through the Chalk forming 

 this bluff, and descends a steep hill. Some 15 to 20 feet of Chalk 

 is thus laid bare on the roadsides, and a careful examination of 

 this has convinced me that the whole of the material exposed is 

 much disturbed : in fact, the Chalk is shattered to a breccia' or 

 conglomerate of Chalk pebbles in a marly matrix. The top portion 

 is much mixed and is full of flints, many large and green-coated 

 (from the Thanet Beds), the bedding-planes of the Chalk being 

 wavy. The surface of the latter is very irregular, and is covered 

 by sand and gravel (pockets of which also occur in the Chalk) ; 

 and above the gravel in one place buff and grey loam occurs. 

 This shattering and loosening of the otherwise very firm Chalk 

 accounts for the whole section being pale red in colour, owing to 

 the percolation of ferruginous waters (not merely down the joint- 

 planes, as is usually the case). The disturbance probably accounts 

 for the many ' pipes ' formed here by root-action. It is note- 

 worthy that at this hill the surface of the Chalk is about 120 feet 

 above O.D., whereas its ordinary level in pits and borings in the 

 immediate neighbourhood is about 100 feet above O.D. 



(c) Descending the valley, the next projection of importance that 

 we reach is on the right bank at Baylham. The Chalk-pit east of 

 the high road shows much disturbance of the strata, and has been 

 figured by Mr. G. Slater. 1 



(d) At Claydon, on the left bank, an important bluff occurs, and 

 luckily a large Chalk-pit is excavated in it. The remarkable section 

 here, illustrating the work of the valley-glacier, was roughly figured 

 and described by Mr. W. Whitaker, 2 and later carefully worked 

 out and drawn by Mr. Slater. 3 



(e) The spur near Old Hall, caused by the union of the small 

 Akenham Brook with the main stream, contains a pit in shattered 

 Chalk, but reference will be made later to the results of mapping 

 this area in detail. 



(/) We meet no other striking sections until we reach the 

 curious spur on the left bank, a short distance north-east of 

 Sproughton Church, However, the 6-inch mapping of the right- 

 bank from Little Blakenham, through Bramford to Sproughton, 

 brings out many anomalies, and there seems to be a probability 

 of disturbance east and south-east of Sycamore House, and on the 



1 Slater, 1907 (22) pi. v, fig. 12. 



2 Mem. Geol. Surv. 1881 (8) p. 10. 



3 Slater, 1907 (22) pi. v, fig. 7. 



