Dr. S. Woodward — New Carboniferous Trilobites. 483 



intervening country between this and Wensleydale (=Yoredale) 

 had been mapped in detail, the name was removed from the index 

 in the later edition of 1891. 



" It was not found practicable where, as in this case, the incon- 

 stant Pendleside Limestone and Pendleside Grits (see Table supra) 

 were absent, to draw any definite boundary between the ' Bowland 

 Shales ' above and the ' Shales-with-Limestones ' below, and both 

 were coloured the light-blue shale colour." 



In his paper referred to Mr. Tiddeman writes: — "Until the 

 area of which we now speak was carefully surveyed it was 

 assumed that there was a rapid transition of type in the Carboni- 

 ferous rocks between Clitheroe and the big fells north of Settle 

 and Malham ; but as to the cause of such a rapid change no ex- 

 planation was forthcoming. Even Prof. Phillips, who knew the 

 country perhaps best of any among the old pioneers of Geology, 

 often expressed himself to me as quite unable to account for it. If 

 there is one thing more clearly brought out than another by the 

 mapping in detail of this ground, it is this, that there is absolutely 

 no transition from one type to the other. The two types run un- 

 changed in their respective areas and with complete discordance 

 ■with each other, quite up to a common boundary where the differ- 

 ences are rather accentuated than smoothed down. They might be 

 Jews and Samaritans, agreeing in nothing save a common boundary 

 to their territories and a determination to have nothing to do with 

 one another. 



"The line of demarcation is given by the Craven faults, and more 

 particularly by that which runs by the south end of Malham Tarn, 

 and that which passes between Malham Cove and Malham." 



" The rocks on both sides of these faults seem to have been formed 

 on slowly subsiding areas, but the Bowland area appears to have 

 been subsiding more quickly and to a greater extent than the area 

 occupied by the Yoredale type. It represents the downthrow side 

 of the faults. The other side of the faults, of course, is relatively 

 an upthrow " (see Table supra, York. Geol. Soc. Proc. 1890, voL xi. 

 pt. 3). 



The subjoined brief note of the locality was drawn up for me 

 by Mr. Pollen a year ago, and I now reproduce it in his own 

 words, with the section of the beds which he also caused to be 

 made for me with the kind assistance of Mr, van der Gracht. 



Mr. Pollen writes : — " The Kiver Hodder makes a straight run of 

 about half a mile, in a direction E. by S., having Hodder School 

 ('Hodder Place,' on the Ordnance Maps) on the right bank. 

 Beneath this house the bank is very steep and high, but there is a 

 broad shelf at the bottom on which are built the bathing-cots of 

 Stonyhurst. The rock all along here is limestone, very crystalline 

 and with much chert, alternating with clay-shales. The total thick- 

 ness of the 'Yoredale series' ^ here is certainly over 500 feet, but the 



^ I retain the term " Yoredale series " here in copying Mr. Pollen's note, although 

 we may follow Mr. Tiddeman in considering them to be lower down in the series 

 than was supposed twenty years ago, when the country was originally mapped by the 

 Geological Survey. 



