A HISTORY OF SUSSEX numerous fish, and a fine series of plants, which last have been care- fully studied by Mr. Seward/ These plants consist of ferns, cycads and conifers of Jurassic types, but include none of the higher flowering plants which mark, the incoming of the Lower Cretaceous period abroad. Whilst recognizing the strikingly Jurassic appearance of the Wealden animals and plants, it should not be forgotten however that truly marine fossils, on which our geological classification is mainly based, are practi- cally unknown in the Wealden strata. Until its marine fauna is better known the exact relation of the Wealden to the Upper Jurassic and Lower Cretaceous of other regions must remain somewhat doubtful. The absence of lime and of certain compounds necessary for plant life, as well as the common occurrence of poisonous iron salts, make most of the country occupied by Wealden strata very infertile and more fitted for oak forest or permanent pasture than for tillage. Where orchards or fruit or hop-gardens thrive it will generally be found that the underlying strata are buried under several feet of superficial ' Drift,' which quite alters the character of the soil. The Hastings Sands form undulating country with steeper slopes than those of the Weald Clay, the beds of sand forming ridges roughly parallel to the folds with east and west axis, which are so marked a feature in Sussex geology. They rise in places to considerable heights, as will be seen on comparing the geological with the orographic map. There is one important product of the Wealden strata that should be mentioned, though it will again be referred to in a later volume in the section on ironworks of the Weald. For many centuries the Weald was one of the most important iron-producing districts of Britain, the ore commonly used being the clay-ironstone nodules at the base of the Wadhurst Clay. These were dug in bell-pits of no great depth, and worked with oak charcoal, which yielded steely wrought-iron of excellent quality. Later on a considerable quantity of cast-iron was made ; but the industry was finally abandoned in the early part of the nineteenth century, owing to the growing scarcity of charcoal and the gradual introduction of coal and of the associated Coal Measure ironstone." There is another product of the Wealden strata that deserves mention. Two borings for water at Waldron, the one at Heathfield railway station, the other at New Heathfield Hotel, struck inflammable gas in the Fairlight Clay.^ This gas seems, according to the analysis by Mr. S. A. Woodhead, to be a genuine petroleum derivative, containing 72 per cent of marsh gas, mixed with enough oxygen (18 per cent) to make it slightly explosive. The gas has been used for lighting the rail- way station and offices. As the main dome of the Wealden anticline causes the strata in Sussex to have a general dip to the south, if we leave out the minor I Catalogue of the Mcsozoic Plants in the Department of Geology, British Museum ; The It'cMen Flora (8vo). a W. Topley, 'Geology of the Weald,' chap. xix. (1875). 3 C. Dawson, ' On the Discovery of Natural Gas in East Sussex,' Quart. Jouni. Gecl. Soc. liv. 564-7 1 (1898). 6
