328 JURASSIC. 



/ Oolites of Scarborough district. 



XA /" 11- /-. IV I C//t'w;///c/rt-limestones with Tri^oiiia-htAs at base, 

 D. Coralhne Oohte. \ u- i • t- i i i * 



,, r , I rickermg, Kirkdale, etc. 



20 j5 leet. \ Oohtes of the Howardian Hills (in part), Malton, 



I etc. 



C. Middle Calcareous \ Calc-grit of Filey Brigg, Pickering, etc., Wass 



Grit. 10-45 feet. ( Moor Grit. 



■n, T T • t / Oolites of the Tabular Hills, Hambleton Hills, 



B. Lower Lnnestones / -,^ . , , j / ..\ r.u tlt a- 



I Kepwick, etc., and(nipartjof theHowardian 



H hi t O I'tp 1 Hills. 



' „„ r . ' \ Limestones of Scarborough Castle, Hackness 



20-120 feet. \ ,f r- 1 r. \ ^ 



(Lower Coral Kag), etc. 



.J n ^ ■ i Hard blue calcareous grits, alternating with 



j\, XjOwer \_/aicaieous 1 n • i t i i ixti •*- 



r ■(• Sn-TCn f t i yellowish calcareous sandrock. VVhite- 



^ ■ ( stonecliff, Cayton Bay, Gristhorpe Cliffs, etc. 



The Lower Calcareous Grit is described by Mr. C. Fox Strangways as a 

 massive yellow calcareous sandstone, becoming more shaly towards its lower 

 portion, where it passes into the Oxford Clay. Pie observes that the upper part 

 of the rock is marked by about ten feet or more of soft sandy beds containing lines 

 of siliceous nodules, which have weathered out from the main mass and form 

 very prominent objects in the cliffs at Scarborough Castle, and near Filey ; these 

 rest on a much harder bed, which, although only about three feet thick, stands out 

 in the cliff in a well-marked ridge, and, as suggested by William Smith, it is 

 probably owing to the great regularity of this bed and its greater hardness that the 

 tabular form of these hills in the interior is due.^ 



Mr. Strangways remarks that a curious feature of this formation are the numerous 

 spurs or ' nabs ' into which it has been denuded by the springs and small streams 

 issuing from the Oxford Clay below." On Levisham RIoor the rock has been 

 excavated into numerous " griffs " or narrow gullies with vertical sides ; they are 

 often 30 or 40 feet deep and only a few yards wide, like miniature canons.^ 



Between the Lower Limestone and the Lower Calcareous Grit, there is locally 

 a division known as the Greystone or Passage Beds. The central portion, locally 

 known as Greystone, consists of fissile calcareous sandstone, 20 to 30 feet in 

 thickness. This passes down into loose sandy beds, and it is overlaid by cal- 

 careous gritty and oolitic beds. At Scarborough these rocks are very accessible, 

 and can be easily examined on the north side of the Castle Hill, where the upper 

 portion is so full of Geivillia aviciiloidcs as to well merit the name of the "Gervillia 

 beds." The Greystone beds are to be seen north of Ebberston and Snainton, and 

 in Thornton Dale.'' 



The Coralline Oolite and Coral Rag are grouped together as Upper Limestone ; 

 and at Hackness their thickness is 100 feet. In places the upper part becomes 

 a true Coral Rag, having, as Mr. Strangways remarks, a peculiar rubbly aspect 

 without a trace of bedding, and being largely composed of crystallized carbonate 

 of lime, abounding with corals. 



Dr. Sorby has pointed out that part of the calcareous grit, just below the 

 Coralline Oolite of the Yorkshire coast, contains numerous agatized shells and 

 minute organisms converted into agate, which at first sight present the appearance 

 of grains of sand." 



The Corallian beds have not been traced far south of Malton, in 

 Yorkshire. In Lincolnshire the Oxford and Kimeridge Clays 



^ Explan. Sheets 95 S.W. and S.E. p. 15. The Tabular Hills are a range of 

 flat-topped hills, extending from Scarborough westwards to near Thirsk. See 

 Sorby, GeoL Poly tech. Soc. W. Riding, iii. 169. 



^ Explan. Sheet 95 N.W. (Geol. Survey), p. 47. 



^ Explan. Sheet 96 N.E., by C. F. Strangways, C. Reid, and G. Barrow, p. 47. 



* C. F. Strangways, Explan. Sheets 95 S.W. and S.E. (Geol. Survey), p. 18. 



5 Q. J. vii. I. 



