﻿1850.] HARKNESS ON THE SILURIANS OF DUMFRIESSHIRE. 55 



rially from the usual beds of the Silurians of the district. The deposit 

 here consists of a soft, grey, shivery shale, in which nodules of lime- 

 stone abound, and in these nodules the fossils are commonly to be 

 met with. A list of these fossils is given at page 206 of the fourth 

 volume of the Quarterly Journal of the Geological Society. Since 

 they were examined by Mr. Salter, three other fossils have been 

 added by Mr. Fleming, which he had not then obtained — two species 

 of Favosites and a Catenipora. This shale with its imbedded no- 

 dules is overlaid by thin-bedded, fine-grained greywacke sandstone, 

 and a similar deposit occurs below it. Still further to the west, and 

 within the entrance of the bay, another bed of fossils is found. The 

 strata here are composed of dark greywacke flags, resembling those 

 at Howell Point, and in these also Graptolites occur. The most com- 

 mon species is the G. Ludensis, Murch. ; but along with it the 

 G. taenia, Sow. and Salter, and G. foliaceus, Murch.?, both found in 

 Wigtonshire, are met with. 



The stratification of the Silurians in this neighbourhood is well- 

 marked, the strike being in an east and west direction. The strata, 

 however, are much confused as to dip, sometimes inclining north- 

 wards at a high angle, and at some places southward, with numerous 

 instances of perpendicular strata in the intervals. The most pre- 

 vailing dip appears to be towards the south, the nearer we approach 

 the coast : the strata along the bay, being traversed by dikes of 

 felspar-porphyry and trap, owe their confusion of dip to this circum- 

 stance. Taking the prevailing inclination as southward, we have, 

 so far as the fossiliferous beds are concerned, first and lowest, a de- 

 posit containing three species of Graptolites, but from which other 

 organic remains are excluded. This bed rests upon greywacke flags 

 and sandstone of a light grey colour and more earthy character than 

 the Dumfriesshire greywacke, and than that also which is met with 

 in the more northerly parts of Kirkcudbright. These beds in 

 their lower portions are intersected by numerous dikes of igneous 

 rock. Above these lower graptolite flags we have greywacke sand- 

 stones and flags of considerable thickness, devoid of fossils ; but 

 resting on these is a soft grey shale, with limestone nodules, con- 

 taining fossils of different kinds. Above this second bed the higher 

 graptolite flags with Orthocerata occur, separated from the middle 

 bed by greywacke flags and sandstones of comparatively little thick- 

 ness. No beds superior to these are exposed ; but to the east, near 

 Netherlaw Point, the representatives of the mountain limestone are 

 seen between the Silurians and the sea ; and at Mullock Bay, near 

 the point of contact of these two formations, Graptolites occur in 

 the former rock, similar to those at Howell Point. 



The general character of the fossils in the deposits about Balmae 

 is such as to indicate an intimate relation between the Wenlock shales 

 and this portion of the Silurian ; and as the beds here are highly in- 

 clined, and as a considerable distance also occurs between the fossili- 

 ferous deposits and the porphyritic district on the north of the parish 

 of Kirkcudbright, which is occupied by the Silurian formation tra- 

 versed and altered by igneous rocks, it is probable that in this 

 interval some of the representatives of the Lower Silurians may be 



