A HISTORY OF LEICESTERSHIRE systematic study of these rocks was undertaken. In this year the first of the well-known papers by Professor Bonney and the Rev. E. Hill was published, followed in 1878, 1880, and 1891 by further accounts of this district. 1 These were supplemented in 1896 by Professor Watts, who proved the general succession of the rocks, and worked out their physical structure in such a manner as to allow the various sub-divisions to be represented on a geological map.' Charnwood Forest is composed of a series of craggy hills and ridges standing out from a fairly uniform surface. These hills are uncultivated and usually devoted to plantations ; while the spaces between, which are thickly covered with angular detritus, are generally enclosed and cultivated. Professor Watts has shown that these rocks existed as islands in the Triassic and Carboniferous seas, and most probably stood up as mountains on the land in Old Red Sandstone times. Their features are not those of the present day, but date back partly to the subaerial denudation of Old Red Sandstone and probably earlier times, and partly to the aqueous denudation of Carboni- ferous and Triassic times. Present day denudation by clearing out the Triassic debris has done little more than expose to-day a pre-Triassic landscape. 8 The rocks of Charnwood Forest are the oldest known in the Midlands. They consist of a thick mass of clastic volcanic rocks with overlying grits and shales ; they are intruded upon in places by several types of igneous masses, and the whole of them are of pre-Cambrian age. They have been classified by Professor Watts in the following sub-divisions* : f Swithland and Groby Slates. The Brand Series . J. Conglomerate, Grit and Quartzite. ( Purple and Green Beds. 1 Olive Hornstones of Bradgate. Woodhouse Beds : Hornstones and Volcanic Grits. Slate Agglomerate of Roecliffe. Hornstones of Beacon Hill. Felsitic Agglomerate. The Blackbrook Series Hornstones and Volcanic Grits. The succession is clearest in the eastern part of the district, but it becomes much more confused in the north-west from the fact that this region appears to have been the focus of volcanic activity, and consequently the rocks are here much disturbed and faulted. The rocks consist to a large extent of volcanic ingredients, even the fine hornstones and slates being made of volcanic dust often interleaved with tuffs and breccias. No traces of organic remains have been found in any of these rocks with the exception of a worm burrow discovered by Professor Lapworth in the slates low down in the Brand Series, and a few other examples since obtained by Mr. Rhodes. The igneous rocks of Charnwood Forest are extensively quarried for road-metal and paving setts ; a large trade is also carried on in artificial flag- stones made from the ground-up rock mixed with cement. 337-5<> ; xlii, 7 8- IOO .
