602 MR. R. D. VERXON ON THE GEOLOGY AND [DeC. I912, 



a pale grey to a dark slaty blue and sometimes to red, and 

 frequently containing cavities filled with green marl ; while spe- 

 cimens of Spirorhis may often be distinguished by the unaided eye. 

 Under the microscope a large amount of argillaceous matter can 

 be detected, particularly in the darker varieties, while careful 

 search nearly always reveals the tests of ostracoda. A diligent 

 examination of other beds (particularly the thin upper bed) has 

 failed to reveal a single fossil. Indeed, there is reason to believe 

 that some of these limestones are, in part, of inorganic origin, 

 and that their formation may be largely the result of chemical 

 precipitation. In describing the jN'orth Staffordshire examples, 

 Ward (see Gibson, 05) proposed the term ' Entomostracan Lime- 

 stone,' for those beds in which ostracoda abounded to the ex- 

 clusion of Sph^orhis ; but, as ostracoda and Spirorhis almost 

 invariably occur together, this distinction appears to be somewhat 

 arbitrary. 



Most of the Spirorhis Limestones, whether in the Nuneaton Clays, 

 in the Haunchwood Sandstones, or in the Keele Beds, are merely 

 impersistent lenticular bands. Onlj^ one bed can be proved to 

 extend over the whole district; it is that laid down on the old 

 Geological Survey maps, and, in this paper, is taken as the base 

 of the Keele Beds. On the line of outcrop sections can still be 

 seen near Biddies Wood, near Kingsbury; in the stream at Monk's- 

 Park Wood, near Merevale ; and again at Longford, near Coventry, 

 where, at a depth of 75 feet, the limestone forms the floor of the 

 Foleshill Clay-pit. This occurrence shows that the outcrop has, at 

 this point, been placed too far to the east on the Geological Survej' 

 map. This bed was formerly worked at Arley, but no section is 

 now visible there. 



Within the basin this Sjnrorhis Limestone has been proved 

 in the following colliery-shafts and boreholes : — 



I)e])ths in feet. 



Exhall Colliery, near Bedworth 340 



Well-section near the Griff Clara Collierj-, Nuneaton 60 



Tunnel Colliery, Stockingford \ 286 



Baddesley Colliery (Stratford Pit) 148 



New sinking at Biddies Wood, near Kingsbury 250 



Whitmore-Park Boring, near Coventry 1637 



Keresley Boring 1413 



At Baxterley a second bed of limestone crops out about 150 

 yards south-west of the main limestone, which was proved in the 

 colliery-shaft at that place. In the south this bed is probably re- 

 presented by a limestone which occurred in the Keresley Boring at a 

 depth of 1306 feet — that is, 107 feet above the main limestone. 



The third limestone is a nodular bed, from 2 to 6 inches thick, 

 which crops out near Maxstoke, and again near Brook End and 

 Nether Whitacre. This bed is possibly the equivalent of the lime- 

 stone which occurs in the Keresley Boring at a depth of 499 feet 

 (that is, 914 feet above the main Spirarhis Limestone), and of a 

 similar thin limestone in the Whitmore-Park Boring at a depth of 

 855 feet (that is, 782 feet above the main Sinrorbis Limestone). 



