550 PKOF. E. J. GAKWOOD ON THE LOWER CARBONIFEEOTTS [DeC. I912, 



Zone at Shap, does not make its appearance at Bavenstonedale 

 until the middle of the Lower Productus-corrugato-hemis])hericus 

 Sub-zone ; it also persists up to a higher horizon in the former 

 district than in the latter. At the same time, the actual thickness 

 of the sandstone series is greater in the southern than in the 

 northern portion of the area. As a result of this incursion of 

 arenaceous material, the normal faunas are very much reduced, or 

 entirely absent from the horizon at which it occurs. 



The secoud important change in the lithology of an horizon when 

 traced laterally occurs in th.^JJ^'^ev Dihunophyllmn Sub-zone. This 

 sub-zone presents two distinct facies, each of which has a separate 

 geographical distribution : a northern and eastern facies, charac- 

 terized by a Yoredale type of deposit, and consisting of a series of 

 bituminous limestones, separated by shales and sandstones ; and a 

 southern and western facies (situated in the neighbourhood of 

 Kirkby Lonsdale, Carnforth, and Gleaston), characterized by the 

 absence of the typical series of Yoredale limestones, by the presence 

 of a bed of true crinoidal limestone in the middle of the series, and 

 by the local occurrence (in the upper part) of crystalline and 

 brecciated limestones, which resemble the knoll-reef limestones 

 of the Cracoe district and contain a similar fauna. 



A third type of deposit, which is only met with at Botany, in 

 the Middleton portion of the Pennine District, consists of a series 

 of fine limestones and cherty calcareous shales lying high up 

 in the Millstone Grit Series. These beds constitute an important 

 fossiliferous deposit unknown elsewhere in the ISTorth of England, 

 containing a fauna characteristic of the higher portion of the 

 Derbyshire limestone-massif. 



The Flora and Fauna. 



Of the organisms Avhich contribute to the deposits, corals and 

 brachiopods are by far the most im2)ortant, but foraminif era are 

 present in nearly all the deposits, and are frequently abundant ; 

 ostracods and bryozoa are also locally plentiful in the more argil- 

 laceous layers. 



One of the most interesting facts brought out by a microscopic 

 examination of the rocks of this area is the important part played 

 by calcareous algae in the formation of the more compact and 

 porcellanous layers of the deposit. The genus Sohnopora, which 

 occurs so universally in the lower portion of the AtJiyris-glabristi^ia 

 Zone, is of peculiar interest, not only on account of the part that 

 it plays as a rock-builder, but also on account of the fact that it 

 has not previously been recorded from any formation between the 

 Ordovician and the Jurassic. Its discover}- here assists, therefore, in 

 bridging over the gap previously existing in the history of its vertical 

 distribution. Another form, Girvandla, appears to have borne 

 a large share in the formation of the nodular band so character- 

 istic of the base of the Upper DihunophyUum Sub-zone throughout 



