426 MR. s. s. BUCKMAN ON [vol. Ixxviii, 



elevation and erosion, _yet prior to another period of elevation and 

 erosion. The second erosion obliterated all these intervening strata 

 from certain places, yet was so adjusted that they were jDreserved 

 in other places. But the latest bed of all is only preserved over a 

 rather limited area — Cleeve Hill, — and strata which ought to follow 

 on this bed, preceding those of Garanfiana hemera, have been 

 completely destroyed. 



It is not necessary to assume that a fault was present until the 

 date which let down the White Bed to its present position — long 

 after FuUer's-Earth date presumably.^ All that need be assumed 

 is a gentle fold bringing Bridport Sands first to the level of the 

 Red Bed, and then to the level of the Zigzag Bed : the actual anti- 

 clinal axis being about on the present line of fault, which would 

 give a syncline just beyond it sufficient to let in the White Bed. 



We do not know how thick the White Bed was originally. Say 

 that there is now some 2 or 3 feet of it preserved. It may have 

 been deposited to a thickness of 20 feet, of which only this small 

 portion is preserved, and that by an accident. It is true that 

 the other Inferior- Oolite rocks of Burton Bradstock are quite 

 thin ; but this is no measure of their original thickness — it is 

 the result of the constant denudation that they underwent, being 

 removed almost as fast as they were deposited. Some of them 

 thicken considerably only a short distance inland — awa}^ from the 

 axis of the Weymouth Anticline. 



For instance, at Vetney (Vinney) Cross, which lies about 3 miles 

 north-east by north of Burton Bradstock (or about 8 miles from 

 the axis of the Weymouth Anticline), the Garantiana Bed is 

 18 inches thick as against 4 inches at Burton or an increase of 

 44 times, while the truellei bed is about 6 feet as against less 

 than 2 feet at Burton; this, however, is not the full thickness, 

 for really the deposit of 6 feet corresponds to about the lower 

 6 inches of the Burton truellei bed, or an increase of 12 times 

 as much. Then at Nettlecomb, near Powerstock Station (about 

 5 miles north-north-east of Burton Bradstock), a rather poorly- 

 fossiliferous quarry shows some 20 feet of schloenhachi deposit, 

 as against less than 5 feet at Burton; and yet there is no sign 

 of the subjacent or superjacent beds, either in the quarry or in 

 the stones of the fields around. 



We speak of the sequence hlagdeni, niortense, Garantiana ; 

 but we have no certainty that this is the complete sequence. 

 It may be that, between the hemerse niortense and Garantiana^ 

 strata were deposited of which no trace has yet been discovered. ^ 



^ The Forest Marble of Watton Cliff contains pebbles of a White-Bed 

 matrix. It is an interesting speculation whether these have been derived 

 from destruction of the Burton or from that of the Watton White Bed. They 

 appear to be rather too soft for either ; but this is a case where chemical 

 analysis might yield some evidence, 



-' The most likely place in this country for such a discovery is near Sherborne 

 (Dorset), in the neighbourhood of the quarries of Frogden and Lower Clat- 

 combe. Seeing how little distance at Burton Bradstock is required to bring 

 in a bed not found in the other neighbouring sections, there is no telling what 

 an excavation at 100 or 200 yards in certain directions near Sherborne might 

 not reveal. This subject may be more fully worked out in a later paper. 



