A HISTORY OF HERTFORDSHIRE most places where there is a large unwaterworn mass it has probably been merely let down into its present position by the removal by denuda- tion of the softer strata beneath it. Large boulders of this rock are frequently found in our rivers, and one such was dredged up from the Ver and erected on the green opposite Kingsbury, St. Albans, in 1887, as the Victoria Jubilee memorial of the village of St. Michaels. The Reading Beds are cut into and their sands and clays are worked in many of our brickfields. Good sections may be seen in the brick- fields near Harefield, at Bushey, in Hatfield Park, and in others along their line of outcrop. Their sands are frequently cross-bedded, indicating shifting currents. They are so very variable that it is impossible to construct a general section. In some places, for instance, there is a thick bed of pure white sand which is altogether absent in others. Of the London Clay only the lower portion is represented ; the basement-bed of brown sandy clay with layers of flint-pebbles, which varies from about 6 to 1 2 feet in thickness, and is perhaps more truly a passage-bed between the Reading Beds and the London Clay than an integral member of the latter ; and a few feet of the lower portion of the true London Clay. This is here a stiff clay rather brown than blue in colour, appearing when freshly cut somewhat like the blue clay under London when that has been exposed for some time. The London Clay is usually capped on the highest points only by a pebble-gravel of Lower Glacial or of pre-Glacial age, in either case the remnant of a bed of gravel once of great extent. Elsewhere it is generally uncovered by superficial deposits, but in the valley of the Stort it is overlaid by chalky boulder-clay. Except in the valley of the Lea below Hoddesdon, where there are sandy loams and low-lying peaty marshes, and also where it is capped by pebble-gravel, the surface-soil upon it is a clay. The area over which the Eocene beds extend presents a marked contrast to the Cretaceous area. Its soils, its agriculture, and its flora are of an essentially Middlesex type. In the Colne and Brent districts it forms grass-lands devoted to hay-farming and grazing, interspersed with woods chiefly of oak, ash, elm, and fir trees ; in the Lea district, on the south, owing to the rich alluvial soil, nurseries and market-gardens pre- dominate ; while on the east, owing to the covering of boulder-clay, the land is chiefly under arable culture, partaking of the character of the corn- growing districts of the adjoining county of Essex. Outliers of the Eocene beds are spread over a considerable area of the Upper Chalk, but there is not one to be seen beyond its limits. Most of these outliers extend in an irregular line which is roughly parallel with the line of outcrop of the main mass with which they have at one time been continuous. As a general rule the larger outliers are towards the north-east, and as they decrease in extent towards the south-west they become more scattered. The largest of these outliers occupies an area of 3! square miles between Braughing and Much Hadham, and consists only of the Reading Beds ; the Colliers End and Sacombe outliers, of less extent, follow near together, the latter of Reading Beds only, the former M
