Vol. 69.] AGE OF THE SUFFOLK VALLEYS. 593 



Ipswich Tunnel appear to have been anomalous in position. 

 Irregularity was noted by the officers of the Geological Survey 

 here, and at the old Stoke brickyard (which has now disappeared), 

 close by on the south. 1 



" (i) Across the valley, on the left bank, there are two spurs 

 projecting southwards into the lower ground, near Dale Hall, 

 north- north-west of the town. Excavations in Messrs. Bolton & 

 Laughlin's brickyard in the more northerly spur have developed a 

 fine example of glacial disturbance, described and figured, with 

 photographs, by Mr. Slater. 2 There are several pits showing much 

 disturbance (sheared and puckered London Clay, etc.) in the 

 southernmost of the two spurs — that of Broom Hill. 



(j) At the eastern end of the town of Ipswich, disturbance 

 was noted and figured by Mr. W. Whitaker in the raihvay-cutting 

 south of the cemetery 3 ; but no good sections have been visible for 

 some time. 



(Jc) In a road-cutting and other excavations in the next hill on 

 the south (that of Grove Lane, Ipswich), Mr. Slater described and 

 figured contortion and ploughing-up of the beds. 4 lied, highly 

 ferruginous, glacieluvial gravels occur here. 



No sections are exposed in the last spur immediately south of 

 Greenwich Farm, neither has this yet been mapped on a larger 

 scale. 



From these observations it is clear that the Gipping Valley is 

 considerably older than the advent of the valley-glacier, and not 

 only the main valley, but also the two or three chief tributary 

 valleys, as shown by the buttressing of the ice upon the spurs 

 formed on the southernmost side at their union with the main 

 valley. The final test of this deduction lay in mapping two of the 

 spurs where no section had been exposed. Like the attempt to 

 map the Hadleigh-Road hill, west of Ipswich, it was found some- 

 what difficult to do this satisfactorily. The first spur chosen was 

 that north-east of Sproughton, and the result was that Glacial 

 deposits, Eocene beds, and Chalk were found to be much mixed, 

 and all at abnormal levels (see Hazel Wood on the 6-inch map). 5 

 The second case was that of the hill near Old Hall, west of 

 Akenham, 4 miles north-west of Ipswich, where similar results 

 were obtained. There is also a chalk-pit here, where the beds 

 appear to be much shattered. 6 The Glacial Drift is so irregular, 

 and members of the series pass so frequently one into the other, 

 that the attempt to draw hard-and-fast boundary-lines on a map 

 often results only in introducing artificialities. The most exact 



i Mem. Geol. Surv. 1885 (10) pp. 11 & 93. 



2 Slater, 1911 (32) p. 13 & pi. vii. 



3 Mem. Geol. Surv. 1885 (10) p. 89 & fig. 25. 



4 Slater, 1907 (22) pi. v, figs. 9, 10, & 11. 

 6 Boswell, 1912 (33) pi. xxxiv. 



Ibid. pi. xxxir. 



