THE CORALLIAN ROCKS OF ENGLAND. 325 



gorges of Yetmandale and Beedale. The basement-beds are gene- 

 rally very thick-bedded and highly ferruginous, as near the Farm- 

 House in Beedale, where we note a variety of Lima gibbosa found on 

 the same horizon at Scarborough. At a higher level, in oolitic road- 

 stone quarries, occurs the obese Ammonites goliathus ; and the main 

 mass of the lower coralline oolites is well exposed in fine quarries 

 about a mile north of Wykeham, though there are few fossils beyond 

 the characteristic Oervillia aviculoides. As we pass a little to the 

 south of Sawdon, towards the boundary of the district, we find very 

 characteristic exposures, not only of the oolites but of the calcareous 

 flags beneath them. These are so ferruginous as strongly to recall 

 the " red beds," weathering into red as they do in the fields, though 

 they are white in the roadways. Several of these beds are much 

 made up of comminuted shells, and are fossiliferous, yielding Ammo- 

 nites cordatus, Cylindrites elongatus (abundant), Dentalium entaloides, 

 Nerinaza, sp. (long and narrow), Exogyra nana, Pecten Jibrosus, P. 

 lens, Perna quad rata, Gervillia aviculoides, Sowerbya triangularis, 

 Rhynchonella Thurmanni. 



The Intermediate Series. — Where the beds above the Lower Calc- 

 Grit are almost entirely calcareous, and the change from the Lower to 

 the Upper Oolite is made through beds so similar that the line of de- 

 marcation is arbitrary, we can expect to distinguish them only in a 

 complete section, which nowhere else can be so satisfactorily made 

 out as in the Forge Yalley. But as we pass westwards and approach 

 an area in which this part of the Corallian Series has a different de- 

 velopment, we meet with signs of the change ; for in Sawdon Lane, 

 overlying the shivery Lower Oolite, according to the dip observed, 

 we see indications of a mass of yellow sandy and purplish blue grit, 

 in places semioolitic ; and overlying this, again, we seem to see the 

 upper portion of the intermediate series at the base of a roadstone 

 quarry, about half a mile N.N.E. of the village of Brompton, where 

 we have the following section, in descending order : — 



ft. in. 



1. Fossiliferous oolites, showing false-bedding. Chemnitzia heddingtonen- 



sis, Trigonia (clavellate and costate), Astarte Duboisiana (common) 4 6 



2. Pale buff grits and oolites mixed. Phasianella striata, Pleurotomaria, 



sp., Exogyra nana, Avictda ovalis, Gervillia aviculoides, Sowerbya 

 triangularis, Lucina, sp. ; also wood, and curious, vertical, root-like 

 markings 6 6 



3. Coarse-grained gritty oolite, with large fossils. Belemnites abbreviatus, 



Ammonites perarmatus, Chemnitzia heddingtonensis (very large) ... 4 



15 



Here bed No. 3, by its large Chemnitzias, reminds us of one of 

 the upper beds of the same series in Forge Yalley. 



The Upper Limestones. — These have long been known at Seamer 

 &c. under the name of Coralline Oolite ; they are well developed all 

 along this range, and have numerous exposures on the hill- sides 

 sloping south. A detailed description of the most accessible and best- 

 known quarry will give an idea of their character. 



