22S MISS G. X. WATNEY AND MISS E. G. WELCH ON THE [May 191 1 , 



III. The Ludlow Beds. 



The Lower Ludlow rocks occupy the greater part of the high 

 ground of the Howgill Fells ; the lower beds pass up conformably 

 into the Bannisdale Slates, which in their turn pass beneath the 

 Carboniferous rocks of Ravenstonedale. An outlier of Ludlow 

 rock, which is not indicated on the Geological Survey map, occupies 

 the summit of Wandale Hill. 



The Ludlow rocks of the Howgill area consist largely of banded, 

 micaceous, sandy beds alternating with grit-bands ; these serve to 

 distinguish the Ludlow rocks from the argillaceous flags of the 

 Wenlock Series. Graptolites are fairly abundant iu the lowest 

 Ludlow Beds, but usually they are poorly preserved owing to the 

 coarse nature of the rock ; exceptions are found in those bands 

 where the fossils occur in relief. 



Dr. Marr 1 has shown that the Ludlow rocks of the Lake Dis- 

 trict may be divided into two main zones, those of Monograptus 

 hohemicus at the base and M. leintivardinensis at the upper limit. 

 Our work in this area supports this earlier classification. 



In addition to the graptolite fauna, lamellibranchs and brachio- 

 pods occur in much greater abundance here than in the Wenlock 

 Flags. 



The Ludlow Beds are most fully developed in the Eavenstone- 

 dale Common area ; but, since the watershed occurs in the Ludlow 

 rocks, no complete section is found, and hence it has not been 

 possible to trace the passage between the Nilssoni and the Leint- 

 ivardinensis Zones. There is evidence of considerable folding on 

 both sides of the watershed, and this is further complicated by two 

 sets of fault-lines which run at right angles to one another, and 

 the great shatter-belt described by Dr. Marr & Mr. Fearnsides. 2 

 Traced upwards from the yellow Phacops-obtusicaudatus Bed, the 

 rocks may be divided into two groups : — 



(1) Blue-grey banded flags alternating with unfossiliferous blue micaceous 



beds which are cleaved and silky in appearance, succeeded by red 

 micaceous grits and flags, with few fossils. 



Throughout this group fossils belonging to the Monogmptus- 

 nilssoni Zone are found. 



(2) Grey banded flags, red grits, and blue slaty beds (the Bannisdale 



Slates) in which M. leintwardinensis is common. 



The outcrop of the greater part of the M. -leintivardinensis Zone 

 is not inserted in the accompanying map (PI. XII), as it occurs 

 farther north, and agrees practically with the line between the 

 Coniston Grit and the Bannisdale Slate on the Geological Survey 

 map. The most fossiliferous development of the lowest Ludlow 

 occurs on Wandale Hill. 



1 Geol. Mag. dec. 3, vol. ix (1892) p. 541. * 



2 Q. J. G. S. vol. lxv (1909) pp. 589 at seqq. 



