T. V. Holmes — The Whitehaven Sandstone. 411 



under the lowest Spirorbis limestone," Mr. Kendall simply replies — 

 '• But surely mere thickness of strata cannot, of itself, determine 

 geological level." 



It is to be regretted that the boring did not go deep enough to 

 show us the nature of the rocks on which the Whitehaven Sandstone 

 rests at Frizington Hall, so as to enable us to note the resemblances 

 and differences in that respect between that place and the cliffs of 

 Whitehaven, and possibly obtain information as to an increase or 

 decrease of the unconformity eastward. A point of interest in the 

 Frizington Hall boring appears to me to be the way in which the 

 section is divided into zones. These consist of an upper one, 

 mainly sandy, between the Spirorbis limestones ; a middle one, in 

 which shales, fireclay, and coals greatly predominate ; and a lower, 

 in which sandy conditions again prevail. And we may also note 

 that in the upper sandy zone the colour is mostly reddish or reddish 

 grey ; in the middle, or shaly zone, the metals and shales are mainly 

 blue ; while, in the lower sandy zone, red and reddish-grey tints 

 again appear almost exclusively. 



I have already remarked that reddish or purple-grey Carboniferous 

 rocks may be seen in North Cumberland on every horizon in that 

 series. And this Frizington Hall section seems to me to point to 

 the probable explanation of this fact, and also to explain why rocks 

 so tinted are almost invariably either sandstones or sandy shales. 

 It certainly gives a very strong support to a theory as to the origin 

 of the purple-grey colour of these Carboniferous beds which I must 

 confess to have looked at, till lately, with some distrust ; I mean 

 the theory that the purple-grey rocks have been stained by the red 

 Permian-Triassic strata which once wholly covered them, though 

 now so large an area of Carboniferous rock lies bare. The Permian- 

 Triassic beds are highly unconformable to the Carboniferous, and 

 rest here on lower, there on higher, members of the older series. 

 Should, then, the older rocks owe their colour to the newer formations 

 once resting upon them, it is obvious that we may expect to find that 

 the lower as well as the higher Carboniferous beds have been stained. 

 We may also expect to find that the rocks are stained or left un- 

 stained mainly in proportion to their permeability or impermeability. 

 In other words, we should expect to see what we do actually see 

 in this Frizington Hall section, sandy zones coloured purple-grey 

 and a clayey zone uncoloured. And this is what we may expect 

 elsewhere. Coal-seams are not likely to be found in purple-grey 

 rocks, because coals are — as in the Frizington section — usually found 

 with clayey, impermeable shales which are not likely to be stained. 

 This section, too, is alone sufficient to refute the notion that there is 

 any necessary connection between purple-grey colour and a certain 

 Carboniferous horizon. 



Another conclusion suggested by this Frizington section is that 

 as the Whitehaven Sandstone, though not low down in the Coal- 

 measures, occupies by no means the highest place, its unconformity, 

 if considerable, is much more likely to have been noted (did it 

 exist) in colliery workings, than would have been the case with 



