BASAL CAilBRIAX EOCKS OF SHROPSHIRE. 391 



from the denudation of the slates amongst which it lies. This is 

 one of the difficulties, but the bedding- is very clear, and there is no 

 proof that these apparent slate elements were ever hardened and 

 formed into rock before being imbedded with the other ingredients to 

 form a grit. The same similarity is seen in an outlier near Smeth- 

 cott ; and near one south of Woolstaston the red grits of the under- 

 lying series are indistinguishable in hand-specimens from those of 

 the overlying. In the absence of any other evidence, this might 

 well be thought to indicate a passage, but it is equally well accounted 

 for by the latter being derived from tlie former and rede])Osited. 



With regard to fossils, the lowest beds look by far the most pro- 

 mising, but the only evidence of life I have seen is some impressions 

 of Liiigulce found near the Church-Stretton Gasworks, but which 

 were unfortunately broken in removal. The purple slates of No. 3, 

 and the pale slates of No. 5 also look hopeful, and it is from these 

 that Salter obtained his best specimens. Ilain-spots and ripple- 

 marks are undoubted, but it does not seem to me certain that the 

 small depressions were burrows made by Annelids, they certainly 

 have no signs of such burroAVS underneath them. They may, how- 

 ever, have been hollows occupied by coiled-up worms. In examining 

 the large specimen figured by Salter (Quart. Journ. Geol. Soc. 

 vol. xiii. pi. V, fig. 1) with me, Mr. E. T. Newton made a curious 

 discovery. The surface of the slab is covered with very fine discon- 

 tinuous curling tube-like bodies, which resemble exactly the castings 

 of minute worms ; indeed I cannot doubt that such is their charac- 

 ter. In these then we have good evidence of the presence of minute 

 Annelids. As to the supposed Trilobites, the evidence is hostile. 

 The slates from whence they are derived are divided by irregularly 

 undulating, overlapping, intermingling surfaces along which they 

 split. These surfaces are remarkably smooth when compared with 

 one produced by fracture. In breaking open the slates, these smooth 

 surfaces come to be bounded by their junction-lines with old fracture- 

 surfaces, and these have often a pseudo-regularity. This, combined 

 with the peculiar undulation of the smooth surfaces, gives rise to a 

 hundred fantastic shapes, and it is one of these surfaces that has pro- 

 duced the specimen figured by Salter as the tail of Palo'opjfrje^ and 

 another the s])eciracn referred by him to the head of Dilceloceplialas 

 (Mus. Pract. Geology). No Trilobitic remains have as yet been 

 made known. What has given rise to these curious smooth surfaces 

 of separation it is difficult to say ; possibly it may be an excessively 

 fine sediment coating a series of ripple-surfaces, or possibly, but not 

 probably, fragments of some kind of laminarian alga. They may 

 even be structural surfaces produced after the consolidation of the 

 rock. 



The area assigned to these rocks in my map extends a less distance 

 to the north than is indicated on that of the Survey, because I have 

 taken notice of the thick masses of drift which conceal what ma}'- 

 lie beneath ; and, tlmugh the underlying rocks may belong to the 

 same series, it is impossible to draw the lines between subdivisions 

 where nothing is seen. The mass ex[)Oscd to the North of Smethcott 



2f2 



