266 C. LAPWORTH ON THE MOFFAT SERIES. 



wrinkled and dislocated character of the Moffat rocks in any single 

 exposure can fail to appreciate at its full value. 



i. First or Muckra Band. 



The most northerly of the black bands of this subregion runs 

 parallel with the course of the upper Yarrow, from the immediate 

 neighbourhood of St. Mary's Loch, crossing the watershed about 

 midway along its course, and finally disappearing above the farm of 

 Bodsbeck, opposite the central point of the Moffat valley. 



Crosscleuch (fig. 5). — Half a mile to the south-west of St. Mary's 

 Loch this band crosses the small stream known as Whitehope Burn, a 

 short distance above the farmhouse of Crosscleuch. Here a little rill 

 enters the barn from the east. At its mouth occurs an exposure of 

 grey shales with black bands, traversed by a dyke of greenstone, but 

 dipping steadily to the northward below the greywackes of the 

 neighbourhood at an angle of about 45°. The presence of numerous 

 white- clay bands in the grey and black beds enables us at once to 

 identify them provisionally with the highest bands of the Birkhill 

 Shales. This identification is fully verified by an examination of 

 their included fossils, which embrace, among others, Rastrites maoci- 

 mus (Carr.) and Monograptus Halli (Barr.), forms strictly peculiar 

 to the highest zone of the Birkhill Shales of Dobb's Linn. 



Fig. 5. — Section above Crosscleuch. 



S.E. „ , S.W. 



D. Flagstones and greywackes of the country. 



Cb'. Grey and purple shales faulted and shattered. Monograptus Hisingeri,&c. 

 Cb 2 . Grey shales, with seams of black and white mudstones, well bedded, con- 

 taining Rastrites maximus, E. hybriclus, Monograptus spinigerus, M. 

 Halli, &c. 

 Ca. Black carbonaceous flags and shales, with Diplograptus vesiculosus, &c. 

 * Dyke of greenstone. 

 /. Fault. 



Immediately to the south these shaly strata are underlain by con- 

 voluted black shales with M. spinigerus (Nich.), beyond which they 

 are repeated and form the right bank of the stream for several yards. 

 Passing over a few fragmentary patches of greywacke in the bed of 

 the burn, indicative of the presence of a small synclinal, the Moffat 

 Series again rise to the surface. At the foot of Thirlstane Burn, a 

 few yards beyond, we come suddenly upon a boss of hard flaggy 

 black shales, which both in appearance and stratigraphical position 

 agree precisely with those at the summit of the D. -vesiculosus band 

 of the Linn. They yield also its characteristic fossils, D. vesiculosus 

 (Nich.) and C. innotatus (Nich.). They are succeeded to the south 

 by isolated fragments of black rock showing the peculiar variegated 

 lines of the M.-gregarius zone, and affording M. tenuis, C. scalaris, 

 and others of its commoner fossils, and the section is closed by a 



