1856.] HARKNESS — LOWEST ROCKS OF ESKDALE. 245 



of the anthracites and the graptolitic shales which are connected 

 with them ; and it would appear that no strata occupying so high 

 a position are developed on this side of the axis in this district. I 

 have hitherto been led to the conclusion, that the beds of Griestone, 

 Peeblesshire, and what I regard as their equivalents in Kirkcudbright- 

 shire, the Barlae flags, occupy a higher position than the anthracite 

 shales and their accompanying graptolite beds ; but, when we take 

 into consideration the flexures to which the Lower Silurians of the 

 South of Scotland have been subjected, and the consequent repetition 

 of the same strata, it is by no means improbable that the Griestone 

 graptolite-flags, and the Barlae deposits aflbrding these fossils along 

 with Fucoids, are inferior in position to the anthracitic shales ; and 

 perhaps they may be the Scottish representatives of the fucoidal 

 sandstones which underlie the graptolite-beds of Sweden and Nor- 

 way*. There is one circumstance which serves to support this 

 inference as to the inferior position of the Griestone and Barlae flags, 

 which is based on fossil evidence, — this is the occurrence of the 

 hitherto almost purely Scotch fossil, the Protovirgularia, in these 

 beds and in the low-lying reddish-purple shales which are found 

 near the axis f. The anthracite and graptolite schists, which abound 

 in fossils, have as yet never afforded the genus Protovirgularia in 

 Scotland, and its appearance in the low beds would tend to the con- 

 clusion that it is a fossil characteristic of a low zone among the 

 Lower Silurians of the South of Scotland. 



Formerly I was disposed to consider the several parallel bands of 

 anthracite-shales as the result of faults : I now consider that they are 

 the products of flexures, — a cause assigned for their occurrence by 

 Sir Eoderick Murchison J, — which would also account for these beds 

 sometimes lying above, and at other times below, the flaggy beds of 

 Griestone and Barlae. 



The inferior position of these latter strata is also supported by the 

 occurrence in them of a species of Olenus, which I found in these 

 deposits last summer at Corfarding, in Penpont parish, Dumfries- 

 shire. 



Hitherto the lowest beds in the Lower Silurians of Scotland which 

 have furnished animal remains are the graptolite and anthracite 

 schists and the flaggy beds of Griestone and Barlae, and their equi- 

 valents. 



The position of the strata more immediately referred to in this 

 memoir is lower than either of the deposits just mentioned, and in 

 them we have the earliest traces of animal life which have been de- 

 tected in Scotland, and these may be looked upon as amongst the 

 earliest records which we possess of organized existences. 



* ' Siluria/ page 318. 



t This form has been met with associated with the " larger Nereiies" in Thii- 

 ringerwald ; see Sir R. I. Murchison and Prof. Morris's Memoir on the Palaeozoic 

 Rocks of Thiiringerwald, Quart. Journ. Geol. Soc. vol. xi. p. 413. 



X Quart. Journ. Geol. Soc. vol. vii. p. 163. 



