part 4] JURASSIC chronology. 387 



Diagrams 8, 4, & 5 are sketches to show the general position of 

 the Junction -Bed. Of the face view it may be remarked that on the 

 left, as the Junction-Bed runs out to the grassy slope of the cliff, 

 it diminishes in thickness and seems to peter out at the surface : 

 this is possibly due to solution by humic acid and the removal of 

 the clayey capping, and it accounts for the bed not making any 

 feature in the slope of the cliff. However, the bed was detected 

 in the ploughed field immediately north of the fault-corner, a 

 little way down the hill. 



(B) The Junction-Bed of Watton Cliff, or, as it may more 

 conveniently be called, the Watton Bed, is now described in 

 detailed section, the result of my investigation. For the results of 

 Mr. J. F. Jackson's examination Appendix I, p. 445, should be 

 consulted. 



Section II — Watton Cliff, near Bridport (Dorset). The Junction- 

 Bed, generalized section with details from various fallen blocks. 



Thickness in feet inches. 

 Xayer 1. Irony scale. ^ Du'inoi'tieriae (I). &&. regularis S. Buck- 

 man, but more distant ribs, D. cf. falcojila Quen- 

 stedt sp.) and belemnites (of tripaiiitus style) 1 



2. White lithographic stone, weathered at the edge to 



look like paper-shales. Peripheries of ammonites 

 of the Grammoceras-striatulum type, but scarce. 

 A Dactyloid (No. 3002) cf. Ammonites crassus Du- 

 mortier, non Young & Bird, ' Bassin du Rhone ' 

 vol. iv (1874) pi. xxvii, figs. 5-7, non cset. Similar 

 forms occur in the variabilis beds of the Cottes- 

 wolds 6 



3. Yellow conglomerate, whiter towards the base. Bro- 



ken fragments of Gram.'inoceras-striatiilnm type, 

 belemnites, Tetrarhynchia tliorncomhiensis. About 

 2 inches from the base Dumo7'tieria sp.^, and about 

 at the base Hildoceras of hifrons type 7 



4. White lithographic stone like No. 2, with a conspicuous 



line of Gramm,oceras of striatulum, type in section, 

 showing peripheries and partly weathered — mostly 

 in the topmost 2 inches. Section of a small Nait- 

 tilus in the rock — an unusual form with a large 

 umbilicus, a cordate whorl- section, the periphery 

 somewhat sharpened. Ham.m.atoceras of insigne 

 type : gastropods 4 



5. Similar to No. 4, sharply irregular at the base. At 



one place the bed is 9 inches thick, at another 

 14 inches. Many specimens of Gram,m.oceras 

 thouarsense-striatulum type, about 4 inches from 

 the top, in a somewhat muddy yellowish seam 



^ In one case, irony scale presumably lacking, fine yellow sands rest on 

 layer 2. They contain small belemnites like B. quadricanaliculatus (Quen- 

 stedt), which are also cemented to the top of layer 2. 



^ A micromorph with rounded whorls, undeveloped as to keel, ribs coarse ; 

 like the inner whorls of Dumortieria novata S. Buckman, but the ribs rather 

 more approximate. 



