<390 DE. W. HIND AND MR. J. A. HOWE ON THE [Allg. I9OI, 



beds lithologically and palaeontologically. In addition, there is 

 the iDteresting and pregnant fact that the upper and lower series 

 are separated by an intermediate set of beds, in which are extensive 

 seams of coal and ironstone, pointing to a closer proximity to land 

 •during their deposition than was the case with the beds immediately 

 above or below them, and land itself, indeed, if it be admitted that 

 coal grew in the place. where it is found. The recurring series of 

 sandstones, shales, and limestones point to three sets of conditions : — 

 sandstones, a more rapid current or a position nearer the mouth of 

 the river ; shales, a slower current or a position farther from the 

 river's mouth ; limestone, a pure marine organic deposit in water 

 uncontaminated with sediment, not necessarily any great distance 

 from land, but out of reach of the solid matter brought down by 

 rivers. 



We know something of the old floor, which sank to receive the 

 hasemeut-beds of the Carboniferous Limestones in Ribblesdale and 

 near Ingleton, and farther north near 8hap and beneath Whit- 

 barrow, and from the sharpness of the upturned edges of the Silurian 

 slates we infer that these must have been dry land immediately before 

 they sank beneath the waters of the Carboniferous Limestone sea. 

 We may assume also, from the evidence of the country, that the older 

 rocks of the Lake District were never submerged. It seems to us 

 not improbable that a strip of country passing from the Lake District 

 across the Isle of Man to the Mourne Mountains in Ireland formed 

 a more or less continuous mass of land throughout Carboniferous 

 times. Most of the Western Isles of Scotland and the Highlands 

 were also unsubmerged. Here was the land, probably extending 

 far to the north-east and north-west, which was the source of 

 the sands and mud (sandstones and shales) of the Yoredale Series, 

 brought down by rivers and spread out over the pear-shaped area 

 occupied by the series of limestones, sandstones, and shales, comprising 

 the northern type of Carboniferous rocks. At times when, by some 

 means or other, either oscillations of the land, alteration of currents, or 

 by the formation of reefs or bars, this detrital matter was prevented 

 from being laid down in certain areas; or, owing to depression of the 

 land, river-action was largely minimized, calcareous ooze was thus 

 able to accumnlate over much larger areas, and the fauna which 

 inhabited the clear sea in the south found it possible to advance north- 

 ward again and again, only to be annihilated or driven back by the 

 recurrence of conditiotis unsuitable for its habits. The detrital 

 matter brought down by a large river is spread out over a more or 

 less pear-shaped area which extends from the mouth, some distance 

 out to sea. Marine conditions largely obtain here, but mixed with 

 the marine fauna of this area, plants and other organic bodies, 

 brought down by the river, will be found. The ground occupied by 

 the Yoredale Series forms the distal lobe of such an area, and 

 therefore we find this series with a pure, thick, limestone-boundary 

 to the west and south. Such a conception takes away all the 

 difficulties in the way of explaining the occurrence of the two types 



