H. C. Sargent — Clay-bawh in the Crich Inlier. 407 



whilst a few of the thinnest partings consist for the most part of 

 beautiful, minute, prismatic crystals of quartz without admixture 

 of any ' clay-substance '. All these beds are comparatively thin, not 

 exceeding an inch or two, as a rule, and often much less. 



The object of the present paper is, however, to discuss the origin 

 of the thicker clay-bands, which have already received a certain 

 amount of attention at the hands of geologists, but which differ 

 considerably in structure from any of the foregoing beds. 



Field Relations. 



The limestone of the Crich inlier forms part of the anticlinal fold 

 which trends northward from Belper to Ashover, and its northern 

 portion lies about 3 miles south-east of the main limestone massif 

 at Matlock. 



There are four distinct beds of these clays exposed in the inlier, 

 and they may all be seen in the face of Cliff Quarry, situated under 

 the summit of Crich Hill. The accompanying section shows their 

 positions relatively to each other and to the limestone. 



N.W. S.E. 



Diagrammatic section through Crich Hill. 



Thin-bedded blue limestone, with chert, about 

 First Clay-band ..... 

 Massive limestone, white to grey . 

 Second Clay-band .... 



Massive limestone, white to grey . 



Third Clay-band 



Massive limestone, white to grey, blue near base, about . 50 



Fourth Clay-band . . . . . . . . 6 in. to 1 



Massive limestone, light blue to grey, of which tliere are seen 

 in the quarry ......... 15 



Feet. 

 . 12 

 1 

 . 70 

 1 to 3 

 . 46 

 . 6 in. to 1 



The Geological Survey memoir. North Derbyshire, 2nd ed., 

 1887, gives the thickness of bed !N^o. 9 as 150 feet (p. 82), Avhich is 

 an obvious error. ^ The total thickness of the thin-bedded blue 

 limestone, above the first clay-band, probably does not exceed 65 feet 

 anywhere in the inlier. I have taken the thickness of bed No. 7 

 from the same memoir (p. 82), which entirely omits bed No. 8, 

 although it is at least a foot thick in Cliff Quarry, but now much 

 overgrown. 



The first and second clay-bands are also exposed in Hilt's Quarry 

 in the southern part of the inlier, and a clay-band, which is probably 

 the first, is well seen in a quarry kuown.as the 'Old Quarry', 

 a short distance south-east of Hilt's Quarry. 



^ Cf. C. B. Wedd, Geol. Surv. Mem., Explanation of Sheet 125, 

 1908, p. 18. 



