AUTHOR OF "GEOLOGY FOR ALL", "MOUNT VESUVIUS", "HAMPSTEAD HILL", ETC. HE Geology of Ealing, although simple and easily understood, is highly interesting, and this for three reasons: Firstly, the Ealing district forms a portion of the complex valley of the Thames, every part of which is geologically most instructive, for it is formed by an unusually large number of distinct formations of very varied character, and for the most part highly fossiliferous; and this great and entirely English valley exhibits a succession of physical features as beautiful as they are typical and distinct. Secondly, from the parish of Ealing were obtained some of the earliest of those fossil bones which have revealed the remarkable zoological conditions of the area we now call England in those pre-historic days that geologists call the Pleistocene Period, when elephants and rhinoceroses roamed over Castlebar and Hanger Hills, and drank the waters of the Thames where is now Kew Bridge, and when, moreover, in those waters of the old Thames the monster of tropical African rivers, the hippopotamus, waded and swam. Thirdly, the same deposits. from which those remains of the huge animals we now only associate with Asia and Africa, were unearthed from their long entombment, have given to us in great abundance the tools and weapons of contemporaneous man. The parish of Ealing had, originally, an area of 3,850 acres, extending from the Thames opposite Kew to the Brent opposite Perivale, and from the east end of Ealing Common to Boston Lane, Brentford, thus including the greater part of the site of the town of Brentford. Though this is a large area I will not confine myself strictly to its limits, since the geology of a limited area is often elucidated by facts derived from a neighbouring district. Within the boundaries of the "Ancient Parish of Ealing", the surface of the ground ranges in elevation from 14.3 feet above ordnance datum (sea level) at the river bank by Kew Bridge to 204 feet at Hanger Hill. The area, lying as it does between two rivers, may be said to be in two river valleys, but the Brent valley is only a small subsidiary portion of the great valley of the Thames. A large portion of the whole area of the parish is a very gentle inclined plain, so gentle indeed that to an ordinary observer it appears quite flat, but it rises from 20 feet above Ordnance Datum, at one part of the High Street of Brentford, to 104 feet at Ealing Broadway. The parish church stands at a level of 94 feet, and the entrance to Ealing Cemetery is 61 feet above O.D. Northwards of this southern portion of the area, the land more rapidly rises and culminates in an east and west medial ridge, which thus divides the parish into two distinct physical portions. This ridge is, at Castlebar Hill, 167 feet above Ordnance Datum, and at Hanger Hill, and the Mount, it attains, as has been said, an elevation of over 200 feet (Bench Mark 204 feet). The ground now slopes down rapidly to the north, and then extends an almost level surface to the Brent, by the side of which river the surface of the ground is 55 feet above Ordnance Datum. The 100 feet contour line passes over both Ealing Common and Drayton Green. The geological structure of the Lower Thames Valley has been the result of causes operating during two very widely separated periods. During the former of these two epochs the massive strata of the hills and higher lands of the main valley, and those, too, at a very little depth below the valley bottom, were formed, while during the latter period the valley was excavated to its present depth, and the superficial sheets of gravels, sands, brick-earths, and alluvium, were deposited. This great fact must, therefore, be the basis of a knowledge of the geology of the Ealing district, in which the characteristic geological features of the valley of the Lower Thames are well exemplified. Three geological formations, with probably the remnants of a fourth, constitute the area of the parish of Ealing. These are the London Clay, the River Drift, or Pleistocene, Alluvium, and a little of what may be Glacial Drift. Of these the London Clay is of the former of the two periods, and the others of the later, the very much later, epoch. But even the oldest formation in the Ealing district, the London Clay, is but of Tertiary age, and the stratigraphical position and geological age of Tertiaries will be seen from the accompanying diagram, representing the relative position and thickness of British sedimentary rocks. The London Clay forms, with the exception of a narrow area by the Brent, and some small superficial spreads of gravel, the surface of the portion of the parish north of a somewhat sinuous line extending eastwards, at about 120 feet above Ordnance Datum, from a point on the western boundary of the parish a little to the north of Drayton Green, and passing to the south of Castlebar House, and thence running parallel to, at a little distance to the north, the northern side of Haven Green to Hanger Lane, north of Hanger Lane Farm, and continuing eastwards to the north of Mason's Green, at the eastern boundary of the parish. Some idea of the vast duration of the interval between the London Clay period and the period of the River Drift may be formed from the subjoined table of Tertiary and Quaternary formations, showing those absent in the Ealing district between the London Clay and the Pleistocene River Drift. Thus it will be seen that between the period of the formation of the London Clay and that of the deposition of the gravels, sands, and brick-earths that immediately overlie it in the southern part of the parish, there intervened an epoch sufficient in duration for the accumulation of strata of great thickness and wide-spread extension. During this period, beds of conglomerates in Central Europe of 2,000 feet thickness, and massive limestones having an extension in Europe, Asia, and Africa were formed, and during this period, too, the Alps were elevated 5,000, and the Himalayas 15,000 feet, while immense flows of lava poured forth in the north, giving those great sheets of basalt, that are so conspicuous now in the north of Ireland, the Hebrides, and in the recently explored lands of the Arctic regions. It was also during this prolonged and ample period that the Thames Valley was excavated by the hand of Nature, |