C. LAPWOKTH ON THE MOFFAT SERIES. 263 



The remainder of the cliff down into the bed of the stream is 

 occupied by strata wholly distinct in their general characters from 

 any thing we have hitherto recognized in this locality. They con- 

 sist of soft sandy mudstones, bluish grey, yellow, or even of a pure 

 white, somewhat concretionary where unaltered, and reminding us 

 strongly of ashy shales where indurated and slightly metamorphosed. 

 "With these are associated bands of hard siliceous rock, compact, 

 ringing under the hammer, and weathering into cuboidal fragments. 



Fig. 3. — CraigmicJian Scaurs. (Upper Section.) 



B. Greywackes and flags of the Gala group. 

 Cb. Grey shales, with Bastrites maximus, &c. 



Ca. Black flags, with Monograptus gregarius and Biplograptus vesiculosus. 

 Bb. Grey mudstones, non-fossiliferous. 



Ba. Black slaty shales, with Leptograptus flaccidus, Bicellograptus Morrisi, &c. 

 Ab. Black and grey shales, with Bidymograptus superstes, Thamnograptus 



typus, &c. 

 Aa. Yellow and grey non-fossiliferous shales, with ribs and beds of hard sili- 

 ceous flagstones. 



These peculiar beds contain two bands of hard black shale, each 

 about three feet in thickness. Some of the soft mudstone lines in 

 them yield Thamnograptus typus (Hall), Lasiograptus bimucronatus 

 (Nich.), Dicranograptus ziczac (Lapw.), &c. They therefore ap- 

 pertain to the same general group as our Glenkiln Shales of Dobb's 

 Linn, the stratigraphical position of which is thus demonstrated to 

 be below that of the Hartfell division. 



These are the lowest beds exposed. They are broken by faults, 

 and their interrelations complicated by some irregular contortions, 

 so that it is difficult to arrive at any thing like a reliable estimate of 

 their thickness. They give us, however, an excellent idea of the 

 mineral characters of the Glenkiln group and of its great import- 

 ance in the succession. 



In all probability they are succeeded to the south by the overlying 



