COAL MEASURES BENEATH ESSEX. I 37 



plain of the Middle Danube to the east with the Mediterranean 

 Basin to the south of the main axes of Alpine elevation, then feebly 

 outlined. The range and extent of these areas of deposition con- 

 tinued pretty much the same during the Cretaceous period, during 

 which the Chalk formation of our southern hills, which underlies 

 the Tertiary strata of this part of England, was built up. Then 

 followed further movements, which upon the whole were move- 

 ments of elevation for North- Western Europe, giving us the much 

 more contracted basins, in which the older Tertiary strata (the 

 Eocene) were deposited. Of such strata examples are seen in the 

 sands and clays of the Rye-street brickyards, and in the London 

 clay (the estuarine equivalent of the great Nummulitic Limestone 

 marine formation), which (with its capping of later Boulder-clay) 

 forms the upper portions of nearly all the higher country in this 

 part of England, where the chalk does not come to the surface. In 

 this Eocene period it was that such minor axes of elevation as that 

 of the Weald were developed, though these, doubtless, in most cases 

 were but the further accentuation of such minor folds of the older 

 strata as had been covered up by the secondary or Mesozoic strata. 

 // is wii/i such minor axes of elevation of the older rocks that 7ve are 

 chiefly concerned in estimating the prohahility of the existence of pro- 

 ductive Coal measures under Essex. 



If now we turn our attention to the coal measures in which coal 

 is worked in Britain and in Europe, we find them so distributed as 

 to bear just such a relation to the older Paljeozoic strata as we should 

 expect, from what has been already discussed. Thus we find the 

 great coal measures series of the Scottish Lowlands lying in a great, 

 broad, synclinal trough, the general axis of which (complicated by 

 minor flexures) trends north-east and south-west, between the older 

 strata which rise into the Southern Uplands on one side and the 

 Highlands on the other. The great coal fields of Durham and 

 Northumberland and of Yorks and Notts (on the one side) and 

 that of Lancashire (on the other side) flank the great Penine axis 

 of elevation. The Midland Counties coalfields, which by later 

 crust movements have been thrown into the separate basins of 

 Staffordshire, Leicestershire, Warwickshire, and Worcestershire, may 

 be connected in a series with those of Gloucestershire and South 

 Wales by the coal measures which have been proved in recent years 

 by borings at Burford (Oxfordshire) and Clandon (near Bath), the 

 whole series representing a broad belt of deposition in the Carboni- 



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