part 3] STLURIAX ROCKS OF THE CLUX-FOREST DISTRICT. 235 



and often absent along the margin of the Clun Outlier. It is 

 followed by olive-green shales of considerable thickness — at least 

 350 feet. Towards the base these tend to be very rubbly. They 

 pass gradually upwards into concretionary green marl ; the con- 

 cretionary structure is most typically developed about -50 feet above 

 the base of the shales. At this level the whole rock is built up 

 of large spheroidal masses, from 1^ to 2^ feet in diameter, with 

 concentric layers, which remind one of the well-known spheroidal 

 weathering of dole rite (see fig. 2). About this horizon the 

 Temeside Shales contain bands of ' cornstones.' The cornstones 

 have either been formed in situ, or were produced by the contempo- 

 raneous erosion of thin nodular limestones. They are sometimes 



Fig. 2. — Temeside Shales in the old quarry 300 yards north- 

 north-west of New Invention, shoicintj spheroidal structure. 



L. D. S. photo. 



[The disc is a florin, whence the scale may be inferred.] 



regarded as of algal origin, although no trace of algal structure 

 has been seen in sections cut from the nodules. The cornstones 

 are small, rarely exceeding 1 inch in diameter. Some of them cer- 

 tainly appear to consist of fragments of other limestones, and the 

 bands would be more properly designated ' cornstone conglomerates.' 

 One such band occurs in a quarry north-west of New Invention, and 

 a limestone-pebble containing Favosites sp. was obtained from it. 

 In three separate instances large pebbles of Aymestiy Limestone 

 with Conchidium hnightii and Atrypa reticularis have been found 

 loose on quarry-floors at this horizon ; but considerable search has 

 not revealed similar large pebbles in situ, wherefore their presence 

 may be merely a coincidence and due to glacial or other agents : 

 as, for instance, recent carting of limestone for agricultural purposes. 



