Geological Society. Ill 



1828, and 1829, and are arranged under the beads of the physical 

 features of the county, the geological structure, and the effects 

 produced by causes now in action. 



Physical Features. — The general form of Suffolk is an oblong of 

 about 47 miles by 27, bounded on the east by the German Ocean, the 

 south by the river Stour, the west by the Ouse and Lark, and the north 

 by the Little Ouse and Waveney. It is impossible, says Mr. Clarke, not 

 to be struck with the fact, that whilst some of these river-courses have 

 an east and west direction, others flow from N.N. W. to S.S. E., and that 

 the coast section from Harwich to Orford is nearly parallel with the 

 latter j and he adds, if these observations be extended to Norfolk and 

 Essex, counties similar in geological structure, an accordance will be 

 found in the direction of their rivers and estuaries. 



How far these river channels may be due to dynamical action, 

 operating from below, the author thinks it is difficult to determine ; but 

 he is of opinion that when they are studied with reference to the proofs 

 of violent derangement in the north, east, and west corners of Nor- 

 folk, and the almost unequivocal evidence of disturbance on the 

 coast of Suffolk, there is sufficient reason for assuming, that the 

 drainage of Norfolk, Suffolk, and Essex has been induced by a violent 

 strain acting from below, and throwing the whole mass of the country 

 into a position, by which 1200 square miles of Norfolk and 220 of Suf- 

 folk are drained by the Yare, and about 2000 of the latter county at its 

 south-east corner. 



In addition to these facts, Mr. Clarke says, that the estuaries of the 

 Aide, the Deben, the Orwell, and the Stour, having an average length 

 of 1 1 or 12 miles, meet the fresh water at nearly the same distance 

 from the sea, and at the boundary line of the great continuous bed of 

 diluvium, which covers so extensive an area in that part of England ; 

 only detached patches of greater or less extent being found to the east 

 of the line. 



The Geological Structure. — The formations of which Suffolk 

 consists, are chalk, the plastic and London clays, crag, diluvium or an- 

 cient superficial detritus, and recent lacustrine deposits ; the first occu- 

 pying the N.W. portion of the county, the second, third, and fourth the 

 south-eastern, and the fifth or diluvium, the intermediate part, restingon 

 all the preceding deposits ; while the sixth or lacustrine accumulations 

 are of very local occurrence. 



Chalk. — This formation in the S.E. of Suffolk, is principallyexposed 

 in the banks of the estuaries and rivers, and contains the usual plates 

 and nodules of flints, as well as the fossils characteristic of the upper 

 chalk. In making a well at Harwich, at the depth of 93 feet, and 

 between the white and gray chalk, a stratum 10 feet thick of sandy, 

 gritty chalk was penetrated. The beds are in general nearly horizon- 

 tal, declining gently to the south-east, but they sometimes dip at 

 considerable angles, and the surface appears to have been violently 

 dislocated and worn into deep gulleys, locally called sand-galls. At 

 Harwich in making two wells only 70 yards apart, the chalk was 

 reached in the northern at the depth of 88 feet, but in the southern at 

 64 feet. Where the formation has been denuded by the rivers, the 



