H. W. Monckton — Denudation and Elevation of the Wealden. 395 



writer's somewhat extensive examination of Pteraspidian and other 

 early Chordate types in Britain, Sweden, Russia, and Germany, 

 has led him to the conclusion that Mt/cterops is certainly not related 

 to any of these forms, but is truly an Eurypterid, with which the 

 texture and superficial aspect of the specimen agree precisely. This 

 determination, it may be added, is also adopted by Dr. R. H. Traquair, 

 who informs the writer that he had already suspected some such 

 affinity from a study of the published figure and description. Space 

 prevents any adequate notice of the superb series of Tertiary Mam- 

 malian remains, of which the figures are now familiar to most 

 palasontologists ; and it is to be hoped that ere long these will be 

 provided with the suitable mountings and cases that their delicate 

 state of preservation demands. 



( To be concluded in our next Number.) 



III. — Note on the Denudation and Elevation of the Weald. 



By Horace "W. Monckton, F.G.S., 

 of the Inner Temple. 



IT is. I think, practically admitted that the present condition of 

 the Weald is the result, firstly of marine, and secondly of sub- 

 aerial denudation. A plain of marine denudation was first formed, 

 and the valleys were carved out by subaerial action. 



As the Weald at present exists, we find the lower beds swelling 

 up in the centre of the area from beneath the newer ones which lie 

 around, and we also find that certain of these older beds are thickest 

 in the centre, and gradually thin out towards the north, and probably 

 also towards the south. The older beds in the centre are thus at 

 a higher level above the sea than the newer ones around them. It 

 has been suggested (Topley, Q.J.G.S. vol. xxx. p. 186) that the height 

 of the lower beds in the centre may be due to the manner in which 

 they were deposited, rather than to an excess of upheaval in the 

 centi-e of the area ; but this can scarcely be so, I think : for it seems 

 hard to imagine a series of successive beds deposited most thickly 

 one after another on the same spot, thus forming a high mound — 

 the tendency of deposition being to fill up hollows, not to increase 

 the height of hills. 



If, however, we assume that the excess of deposition was the 

 result of and coincided with an excess of depression, the matter 

 becomes simple. Thus, from some undetermined period until the 

 formation of the Gault, the south-east of England was an area of 

 depression, and the progress of depression was more rapid upon the 

 east and west line which now forms the anticlinal of the Weald than 

 either to the north or to the south of it. If my readers will turn to 

 Mr. Topley's diagrammatic section, plate vi. p. 242 of his memoir 

 on the Weald, they will see that depression was more rapid under 

 Crowborough Beacon than under London ; and as deposition always 

 attempts to fill up hollows, the rate of deposition was higher and the 

 beds thicker in the former than in the latter locality. This was 



