PARTICULARLY OF THE VALLEY OP THE GIPPING. 441 



undoubtedly is so, and yet exhibits a considerable amount of chalk nodules. The chalk of 

 this well must rise very nearly to the level of the river, but at no place nearer than Need- 

 ham does it actually exhibit itself at the surface ; indeed the sand and gravel which forms 

 the foundation of the valley, has not, I believe, been fathomed. 



I have little doubt but that the line of the valley corresponds with a fissure in the chalk ; 

 if so the disturbance producing the fracture must have taken place subsequently to the depo- 

 sition of the drift-clay, otherwise there would be no reason for the coincidence : it is weighty 

 evidence in favour of a still later deposition of the sand, that it cannot be said to have suffered 

 such general disturbance ; its strata are very easily distinguished, and although full of such 

 partial slips and displacements, as would occur in cliffs subject to wear at the base, are upon 

 the whole perfectly horizontal. 



If the preceding observations have been correctly made they would seem best to accord 

 with the supposition that the Gipping valley was formed subsequently to the deposition of the 

 drift-clay, and for the greater part of its course cut completely through the clay : that it 

 afterwards formed the estuary of a very sandy-bottomed sea ; that as the rising of the land 

 or other causes made the water shallower the deposits assumed the character of fine clay, 

 then succeeded a small chalky gravel with broken belemnites, ostrea, &c. (especially indicative 

 of a tranquil beach), and finally came a large mass of drift, boulders and flints — the whole 

 apparently the produce of drift denudation. As the land still rose this deposit was itself cut 

 into, the greater portion carried away, and only its edges left. The floor of the valley thus 

 a second time excavated is very generally covered over with a sandy gravelly rubble in which 

 bones are sometimes found (p. 438, (2) fig. 10); but the larger portion even of this is 

 concealed by alluvial deposit and peat of the meadows. 



Whether or not the real order of events at all resemble this, the continuous line of cliffs on 

 both sides of the valley, some of them carved in the chalk itself (fig. 8), points almost irre- 

 sistibly to a period when the sea level must have remained with some permanence at a height 

 much above the present high-water mark. 



It is probable that the chalk which comes so near to the surface as to be exposed by the 

 channelling of the Gipping valley was the ridge bounding the London clay on the North : 

 the drift-clay clearly overlies it here, and therefore cannot have been stopped in its S. E. 

 course by the same ridge, although it is not now seen to any great extent between this point 

 and the coast : none of the cliff sections (certainly not those at Harwich, Walton on the Naze, 

 and Aldborough) except Lowestoft appear to shew any undisturbed drift-clay at all. 



I have not examined any of the other valleys of the county in so much detail as I have 

 that of the Gipping, but the following very patent facts connected with them are of much 

 importance in any attempt to arrange the various phenomena of the Suffolk Drift. The sections 

 given are most of them from Mr Clarke's memoir printed in the Transactions of the Geo- 

 logical Society (2nd Series, Vol. V.) ; a most valuable paper, but unfortunately not suffi- 

 ciently definite in regard to the localities quoted. The nomenclature is taken from the 

 Ordnance maps. 



The Offton Stream rises about Great Bricett in deep drift-clay, cuts at Offton into 

 the chalk, which is there largely quarried, and continues in it until it joins the Gipping at 



57—2 



