part 1] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxxix 



to Penshurst than to Battle, being thus nearly coincident with the 

 main axis of the superficial anticline (see fig. 2, facing p. lxxx). 



Similarity between the opposite sides of the Weald is also to be 

 observed in some of the outcropping strata, particularly in the 

 Lower Greensand, which is known to thin rapidly towards the 

 Chalk escarpment on the south, as well as on the north, dwindling 

 from 300 to -100 feet in the Arun Valley, to only a few feet where 

 proved in borings beneath the (lault between Eastbourne and 

 Lewes. A corresponding, but less extreme diminution of the 

 AVealden Beds in the same quarter is also indicated, though not 

 actually proved, by the narrowing of the outcrops. 



The southward uprise and attenuation of the Jurassic rocks 

 towards this quarter justifies the supposition that they may thin off 

 southwards against a rising floor of Paheozoic strata in the same 

 way that they have been proved to do on the other side of the 

 basin, and that the limits of the Wealden Anticline are approxi- 

 mately the limits of the buried syncline also. If this be so, it 

 follows that the Paheozoic floor may be nearer the surface in the 

 Tertiary strip south of the South Downs than it is in the Weald, 

 an inference of some practical consequence, which might be worth 

 putting to the test. 



To illustrate this trend of the evidence, I have plotted a section 

 across the Weald, from Sheerness at the mouth of the Med way to 

 the Sussex coast at Beachy Head, as shown in fig. 2. The deep 

 boring at Sheerness gives definite information down to the 

 Paheozoic floor at the starting-point ; at 8 miles to the south- 

 south-east the line passes through the Bobbing Poring, which again 

 entered the Paheozoic floor; and at about 18 miles, on reaching 

 the plain of the Weald Clay, I take the evidence of the Pluckley 

 Boring, which lies 7 miles away to the east, supplemented by that 

 of the Bra bourne Boring for the Middle and Lower Oolites and 

 Lias not penetrated at Pluckley. it will be noticed that up to this 

 point the section reproduces almost exactly the features shown on 

 a larger scale in the previous section, fig. 1 (p. lxxvi), which lay 

 IS miles farther east. 



For the central area I depend largely upon the Penshurst Boring, 

 about 15 miles distant to the westward, projected to the line of 

 .section at the perpendicular which is also the strike of the rocks; 

 but this boring ended in the Kimmeridge (May, and, as before ex- 

 plained, the lower part of the section here is based hypothetically 

 on the Brabourne results. Farther south, the line runs close to 



