1853.] 



HARKNESS KIRKCUDBRIGHT SILURIANS. 



183 



<>2 "li 



^3 ?^ ""^ 



Mary. A little to the east of this place the grits are traversed by 

 veins of sulphate of barytes. At Port Mary the Silurians again 

 make their appearance, and in the course of the small burn are seen 

 dipping S.S.E. at an angle of 55°. 



Immediately west from Port Mary the grits 

 reappeai', and run along the coast to Abbey 

 Burnfoot ; where the silurians are seen, having 

 a north inclination at Guthries Pool. Up the 

 Netherlaw Glen, from whence the burn flows, 

 the inclination of the silurians is the reverse of 

 what occurs at Guthries Pool, being to the 

 south at an angle of 50°. 

 ^ ^ ^^^' £ From Abbey Burnfoot westward the grits 

 again occur, and occupy the coast to Nether- 

 law. Here they consist of red-coloured beds 

 containing rounded and angular fragments of 

 quartz and silurian rock, and have a southerly 

 dip, at an angle of 1 7°, which is the prevailing 

 dip of the carboniferous equivalents in this 

 county. 



At Netherlaw Point commence the series of 

 silurian rocks which it is the object of this paper 

 more particularly to notice. Some of these have 

 been more or less fully described in a former 

 paper* ; but the relation they bear to the de- 

 posits constituting the great mass of the silu- 

 rians of the South of Scotland has not yet 

 been shown. Near the summit of the headland 

 the silurian strata are covered by the carbo- 

 niferous grits, but the point of contact between 

 the two formations is not seen ; they consist 

 of 1. (uppermost) Shale and sandstone; 2. 

 Vl ^^.%. Sandstone; and 3. Graptolite Shale. 



No. 1 comprise, in the Upper part, — light- 

 grey shales (with calcareous nodules), alter- 

 nating with light-grey sandstones, in beds 

 rarely exceeding a foot in thickness. The un- 

 der-surface of the sandstone is ripple-markedf 

 (as seen at Netherlaw and Gipsey Points). 

 This sandstone at Gipsey Point is much coarser 

 than that at Netherlaw Point, of which it is a 

 repetition, and it contains fragments of quartz 

 and jasper, and a fragment also of syenite was 

 found in it by the author, similar to the syenite 



* See Quart. Joum. Geol. Soc. vol. vii. p. 54. 



t These ripple-marks are not of the waved form which usually occurs on 

 ripple-marked sandstone, but consist of irregular hollows and sinuous elevations, 

 often terminating abruptly. A similar ripple-mark occurs on the under-surface 

 of the red sandstones near Annan, Dumfriesshire, where they lie on beds of day. 

 See Quart. Joum. Geol. Soc. vol. vi. p. 397. 



5* "^ 



y.i 



