C. LAPWORTH ON THE MOEEAT SERIES. 291 



turns at right angles to its former direction and lays bare a com- 

 plete transverse section of the Moffat beds of the locality (fig. 21). 

 In spite of the convoluted state of many of the beds, the arrange- 

 ment of the black shales is easily interpreted, and is demonstrative 

 of the infraposition of the Birkhill beds to the neighbouring grey- 

 wackes. To the north the latter form a steep cliff, beneath which 

 the purple shales of the R.-maocimus zone, here barren of fossils, 

 plunge at a very steep angle. Below these the grey and black 

 shales of the M.-spinigerus zone are recognizable. A few of its black 

 bands are here very prolific, swarming with multitudes of Monograp- 

 tus spinigerus (Nich.), M. Hisingeri (Carr.), JRetiolites perlatus (Nich.), 

 Diplograptus Hagliesi (Nich.), &c. 



Similar beds, greatly disturbed, form the floor of the stream for 

 some distance. The lowest grey band is much hardened, and 

 where it finally disappears gives rise to a small waterfall, beyond 

 which the underlying M.-gregarius zone comes to the surface. Its 

 beds form the north bank of the stream above the cascade. It is 

 highly interesting to note the presence in its central division of 

 the thick seam of ironstone nodules so conspicuous at Dobb's Linn. 

 Here also the soft pyritous mudstones which are immediately in con- 

 tact with it swarm with Monograptus triangulatus (Harkn.), Diplo- 

 graptus modestus (Lapw.). 



The overlying M.-spinigerus zone of the Upper Birkhill Shales is 

 much more disturbed than it is on the opposite leg of the anticlinal, 

 but it may be identified both by mineralogical characters and by 

 fossils. The beds of the succeeding purple-shale zone, on the other 

 hand, are admirably exhibited. They dip steadily below the thick- 

 bedded greywackes of the south cliff at a small angle, and yield 

 a few characteristic fossils, preserved with their full relief. 



iii. Eittonside. — Higher up the valley of the Evan, viz. at Middle- 

 gill, Eittonside, and Headshaw, there are additional exposures of the 

 dark shales. The first of these is almost valueless for our present 

 purpose ; but at Eittonside a fairly intelligible section is afforded by 

 the walls of the railway- cutting above the small cottage. Here, as 

 at Belcraig, the Graptolitiferous beds are traversed by an enormous 

 dyke of greenstone, and are greatly shattered. In the centre of 

 the section the hard black flags of the D.-vesiculosus zone are apparent, 

 and furnish, among others, Diplograptus vesiculosus (Nich.), Olima- 

 cograptus scalaris (His.). On both sides they are followed by 

 faulted wedges of the pyritous and variegated shales of the succeed- 

 ing M.-gregarius zone, replete with Monograptus gregarius (Lapw.), 

 Diplograptus tamariscus (Nich.), and their usual associates. Be- 

 tween these and the hard greywackes of the remainder of the cut- 

 ting are some fragmentary patches of purple and grey flaggy beds, 

 which represent the highest or "grey" division of the Birkhill 

 shales. 



iv. Headshaw Linn. — The dark beds are here exposed in the normal 

 score or gorge dug out by the waterfall marking the junction of 

 the Gala and Moffat formations. The majority of the beds are in- 

 tensely metamorphosed, being changed into a soft flaky mass of a deep 



