210 



ME. C. T. TKECHltAKN- ON A JIASS OF ANHVDRITE [June I9I3,. 



At Craggy Bank a good exposure of very fossiliferous rock occurs 

 on the south side of the stream, some distance up the bank. It is 

 here broken up into large and small irregular angular fragments, 

 which however are in undisturbed position. 



At Ivy Rock the following fine section is laid bare in an over- 

 hanging cliff about 80 feet high, where the position of the above- 

 mentioned angular breccia can be seen about the middle of the 

 exposure : — 



Thickness in feet. Fauna. 



f Hard, massive, variable, indurated ~) 



beds, much broken up. Fossili- > 30 Nautilus at the base. 



ferous in places ) 



Highly - fossiliferous angular | -.,. 



Uppee 



Shell- 



Limestoni 



breccia j 



This passes gradually but rapidly^ 

 down into a soft powdery mass, 

 much cross -jointed, enclosing | 

 bands of harder material, in }> 35 

 which the fossils are still recog- 

 nizable in the layers directly | 



underlying the breccia J 



Thin, stratified, soft, uncollapsed 

 bed of porous limestone in the 

 stream 



Highly bryozoonal limestone.. 



*{ 



Casts of Bakevellia ant i qua 

 and small gasteropods. 



The prevailing dip of the Shell-Limestones, about 5° to 10° east 

 wards, brings up the underlying soft powdery beds, until at Whit< 

 Rock they occupy the whole of the cliff on each side of the stream 

 giving a very conspicuous section as follows : — 



Thickness in feet. Fauna. 



Shell f Yellow and white powdery friable^ 

 t " [ limestone. 



,„_ -,„„., ' Lines of stratification distinctly 



MEKGIJSG- I -„/K„„ + „,l k„ T,„„.L. „* 1, „,.,]„',. 



INTO THE 



80 



All traces of fossils appa- 

 rently obliterated. 



j indicated by bands of harder 

 tkatieied j and l^ss altered, but still very f 

 Western porous, limestone. 

 Equivalent. Sec 1 tion P rac t"»% homogeneous 

 (^ throughout J 



Passing downwards and westwards the beds become less altered, 

 the white powdery rock merging gradually into a well-bedded fine- 

 grained limestone. The intermediate phase is well seen in the cliff 

 above the stream opposite Seven Chambers, where the powdery 

 material, accompanied by some calcareous segregation, becomes 

 subordinate to bands of unaltered rock containing fossils. 



Between this place and Gunner's Pool many fine sections of com- 

 paratively unaltered bedded limestones are exposed, representing the 

 equivalents of the Shell-Limestone on the western side of the reef. 



At Devil's Bridge the following section is laid bare : — 



Thickness in feet. Fauna. 



'Well stratified, fine-grained, thinly" 

 bedded, hard, and slightly-fetid 

 limestones. Generally almost 

 unaltered, though brecciation 

 Middle and segregation are present to a 

 Bedded «{ small extent. Strata often very 

 Limestones. much fractured at right angles 

 to the planes of bedding. 

 Flattened hollow spaces (left by 

 sulphates ?) present in some of 

 t_ the less altered portions J 



f Vermes, lamellibranchs 

 j and ostracoda. 



j Bryozoa and brachiopods 

 [_ entirely absent. 



