338 de. A. M. DAYIES AND 3IR. J. PEINGXE ON [June I913,. 



ijiterpretation of Bletchley is abandoned. On the contrary, it is. 

 found at Calvert (and probably at Bletchley) that a non-sequence- 

 occurs between Oxford Clay and Forest Marble, as though the Cal- 

 lovian age were a time of emergence. In this connexion it may be 

 recalled that in various parts of the outcrop there is no evidence 

 of Callovian, while the anceps zone of the Continent is scarcely 

 known in Britain. 1 Along the outcrop, however, the Cornbrash is 

 one of the most constant of formations : its absence at Calvert 

 was a great surprise. 



(7) No later Jurassic overlap is known, and the next is the 

 Wealden overlap, known on the Palaeozoic floor at Ebbsfleet only.. 

 At Dover, Wealden rests upon Kimmeridgian. 



(8) The Aptian overlap (hemera deslmyesii ?) occurs at Culforcl 

 on the north and Cliffe on the south ; also upon Jurassic strata at 

 llichmond, Chatham, Bobbing, and Chilham. 



(9) The Albian overlap (hemera interrupti or later) is shown at 

 Harwich, Stutton, and Weeley, at Ware, Cheshunt, Kentish Town,, 

 and Crossness (and upon Jurassic strata at Saffron Walden, Meux's 

 Brewery, and Streatham). With this, the Palaeozoic floor and its- 

 Jurassic cover were in all probability finally submerged. 



VI. Summary. 



The most important new facts recorded in the present paper are- 

 these : — 



(1) The shallow depth at which the Palaeozoic floor lies at 

 Calvert — 443| feet below the surface, or 153^ feet below sea-leveL 



(2) The presence in North Buckinghamshire of Lower Tremadoc 

 Beds (Shineton Shales) with Clonograptas. 



(3) The absence of Triassic (except possibly in the Western 

 Boring), of Hettangian and Sinemuriau, and the direct superposition, 

 of the Charmouthian (Jamesoni zone) upon the Palaeozoic floor. 



(4) The absence of all but the lowest portion of the Doinerian 

 (Middle Lias of the Geological Survey), of the whole of the Toarcian^ 

 Aalenian, and Bajocian (Upper Lias and most of the Inferior 

 Oolite), and the superposition of a high zone of the Vesulian 

 ( Chipping-Norton Limestone) upon the algovianum (lower mar- 

 (jaritahis) zone of the Domerian. 



(5) The absence of a portion of the Swerford Beds, the Neaeran 

 Beds, and probably of a small portion of the Great Oolite. 



(6) The absence of Cornbrash and Callovian, the ornatum zone 

 of the Oxfordian resting directly upon the Porest Marble. 



1 See S. S. Huckman, 'Summary of Progress for 1911' Mem. Geol. Surv.. 

 3912, pp. 62, 63. 



