Page:VCH Herefordshire 1.djvu/76

 A HISTORY OF HEREFORDSHIRE The Keuper Series is divisible into two parts ; an Upper, and a Lower or ' Waterstones.' The Waterstones are massive-bedded soft red sandstones, but do not occur at the surface in this county. The succeeding beds are marls, usually of a red colour, but frequently variegated. They occupy, in this county, a narrow strip of country along the eastern side of the Palaeozoic rocks of the Cradley district, against which they are faulted. The Bunter Beds were probably accumulated under desertic conditions, in other words under conditions similar to those which obtain at the present day in the deserts of Central Asia and Arabia ; while the main mass of the Keuper Marls is thought to have been accumulated in an inland sea not differing in any marked respect from the Caspian of the present day. The Keuper Marls are the newest ' solid rocks ' in Herefordshire. But subse'quent to the time of their formation there was deposited the vast thickness of clay, limestone, and sand, which made up the Jurassic System. These beds are seen in the Vale of Gloucester, in the Cotteswold Hills, and in the great inclined plain which extends from close to the edge of the Cotteswold Hills nearly to the foot of the Chalk escarpment. The Chalk escarpment shows a great thickness of chalk rock, and knowing also that this is a deep-sea deposit, it seems reasonable to suppose that it once extended much further west than the line of its present outcrop. The probability is that this rock at least extended into Herefordshire, which means that Herefordshire was at that time beneath the sea. Towards the close of Chalk times there was upheaval, and it was such that a plain was formed with a slope from the north-west to the south-east. From the date of this uplift until the present, except possibly for a com- paratively insignificant interval (for which supposition there is little evidence as yet), during the long ages in which the Chalk Beds that are unrepresented in England (the Danian), and the whole of the Tertiary System, were being formed in other parts, the surface of Herefordshire was being sculptured by subaerial denudation. River Development According to the ' theory of River Development,' when the Chalk plain was uphfted towards the close of the Cretaceous Period, it was inclined from north-west to south-east, and was bounded on the south by a range of hills which is now indicated by the Vales of Pewsey and Kingsclere and of the Weald. The River System which was initiated upon this inchned plain had its main river flowing from west to east along the northern slope of this range of hills, and into it— joining i^ on its left bank— were rivers coming from the north-west, and therefore having approximately a north-west and a south- east direction. These primary streams are called ' consequents.' A very little amount of consideration will show that as time progressed these consequent streams would develop tributaries, which would work along the lines of least resistance. That was generally along the strike of the rocks and since the original consequents flowed with the dip, and the strike is at right angles to the dip, the tributary streams would join the parents at right angles or thereabouts. In this way a network of rivers was developed,