GEOLOGY of these zones, that of Am. capricornus and Am. yamesoni, have by some authors been included with the Middle Lias, but it is better to class them with the Lower Lias, as the line of the higher horizon is the only one that can be drawn in the field. 1 The best exposures of the lower part of these beds is undoubtedly in the lime pits at Barrow ; the higher zones can only be made out from obscure sections, mostly along the stream courses. The bands of limestone in the lower part are burnt for lime at Kilby Bridge, Barrow-on-Soar, and Normanton Hills, that from Barrow making a noted hydraulic cement. MIDDLE LIAS The Middle Lias consists of two divisions ; the upper part is a rock bed of ferruginous and sandy limestone, having at Tilton a thickness of about 1 8 ft., while below this are sandy shales and clays occupying another looft. or more. These correspond to the two palaeontological zones of Ammonites (Amaltheus] margarifafus, and Ammonites (Amaltheus) spinatus, and are easily recognized wherever the rock crops out free of Drift. The thickness of the Rock Bed, however, varies considerably in its passage across the county, reaching its maximum development along the western escarpment about Billesdon and Burrow-on-the-Hill ; while it nearly thins away altogether at several points towards the eastern part of its outcrop. Where the Rock Bed is best developed it forms a fine escarpment over- looking the Lower Lias plain, as at Life Hill near Billesdon and at Burrow- on-the-Hill, at both of which places it rises to an elevation of 690 ft. above the sea. North of Melton Mowbray the Middle Lias also forms a bold escarp- ment running from Ab Kettleby by Harby Hill to Belvoir Castle. The Rock Bed is extensively worked for ironstone at Holwell, Eastwell, and Eaton, and was formerly used for roadstone and as a building material. The Rock Bed being a very open porous rock, springs are frequently thrown out at its base, but the water is usually very ferruginous. Where the rock is free of Drift it gives rise to a red soil, which is very pro- ductive, and nearly always under the plough, forming a marked contrast to the clay land above and below, which is always in pasture. UPPER LIAS The Upper Lias of this district has been separated by Professor Judd into the following five divisions s : 5. ' Leda ovum Beds.' Clays with numerous bands of septaria (many fossils) . 4. Highly pyritous clays, with much jet in places (few fossils). 3. ' Communis Beds.' Laminated blue clays with bands containing numerous small fossils. 2. ' Serpentinus Beds.' Clays with nodules of limestone, sometimes ferruginous (ammonites abundant). i. ' Paper shales with Fish and Insect Limestones.' 1 Memoirs of the Geol. Surv.: 'The Jurassic Rocks of Britain,' i, 28 ; iii, 187. 1 Ibid. : ' The Geology of Rutland,' 89. '3
