Pliocene 



Great 

 Oolite 



Burrter 



Permian 



Sjlur- 



Cambria 



11 



- -H +-- 



O o oooo o - 



AVAVAVA 



VA7AVAV 



3473 



Alluvial gravels, blown sands, estuarine mud, boulder clay, 

 and other glacial deposits ; cave earth with recent fossils. 

 Deposits yield peat, gravels, and brickearths Typical localities 

 are Solway Virth. Chesil Bank, Holderness. 



Mainly sands and loams, var ( ous beds of crag. Chief economic 

 products are marl and phosphates. Main districts are Norwich, 

 Cromer, Aldborough. 



Miocene rocks fall into sequence herr They are not repre- 

 sented in Britain, being chiefly found in the Mediterranean area. 



lilding stone, cement, and 

 found IL the Hampshire 



Sands and clays predominate. ] 

 brickearth are obtained. Chiefly 

 basin (Isle of Wight). 



Sands, clays, and pebble beds. Chief clay, London clay, is 

 widely spread over the London basin, and may exceed 450 ft. 

 in thickness. Chief economic products are glass-sands, brick 

 and tile earth. 



Maestricht chalk Is net represented in Britain. 



Chalk andchalk marl, yielding cement and lime, occur mainly 

 in the hill country of the Lowns and Chilterns. Beds may be 

 more than 1,500 ft. thick. 



Mainly sands and clays providing road-metal, cement, and phos- 

 phates. Notable outcrops are found at Leith Hill, Blackdown 

 Hills, Hunstanton, Warminster. 



Chief clay of the Weald, with some sands, containing iron-ore, 

 at Claxby. Away from the Weald, where it is 1,500 ft. thick, 

 outcrops at Swanage and in the Isle of Wight. 



Sands and limestones, yielding building stone and Purbeck 

 marble. Chief localities are Portland, Purbeck, Swindon, and 

 Aylesbury. 



Clay containing fossils of saurians. " Kimeridge coal " yields 

 oil-shale. It occurs at Swindon, in the Vale of Pickering, and 

 Cromarty. 



Limestone and clay with some grits. Chief products are lime, 

 iron-ore at Westbury, etc., and building stone. Main outcrops 

 are at Weymouth, Oxford, Filey, and Brora in Sutherlandshire. 



Clay of the Oxford basin of the Upper Thames, yielding brick 

 and tile earth. Away from the Thames it occurs at Peter- 

 borough and in the island of Skye. 



Mainly limestones yielding lime and local supplies of building 

 stone. The rocks also provide Bath stone, Stonesfield slate, and 

 fuller's earth ; they range from Weymouth to Bedford, East 

 Yorkshire, and Brora. 



Clay and limestone, estuarine deposits, yielding building stone 

 and lime as well as iron-ore at Northampton and Eosedale. Out- 

 crops occur at Cheltenham, Lincoln, and in Skye. 



Limestones, Clays and shales. Economic products are alum, 

 jet, lime and cement, and, notably, iron-ore at Cleveland and 

 Frodingham. The rock is found in Yorkshire, Skye, and Antrim. 

 Besides insect and plant remains it has ichthyosaurian fossils. 



Marls, providing building stone, gypsum, and rock salt. Out- 

 crops occur on the flanks of the Southern Pennines and in 

 Antrim. 



Triassic limestones, musselkalk, etc., are not represented in 

 Britain. 



Sandtone and pebble beds, usually in hilly country Cannock 

 Chase, Bridgnorth. Economic products are building stone and 

 foundry sand. Typical Bunter heath country is found in 

 Sherwood Forest. 



Marls, sandstone and limestone, yielding building stone. Out- 

 crops are found at Dumfries, Penrith, Suuderland and Doncaster. 



Shales with coal and sandstones, yielding coal, ironstone, fire- 

 clay, building, paving, and grind stone. For location see coal- 

 fields map. 



Sandstone, grit, yielding chert, building, mill and paving stone. 

 Outcrops occur in the Pennines, South Wales, and the Mendips. 



Mountain limestone yielding lime, marble in Derbyshire and 

 West Meath, lead-ore, and cement stone. The rock is responsible 

 for scenic beauties in Derbyshire, the Mendips, the Isl-i of Man. 



Sandstone and marls with local limestones, yielding marble, 

 slates at Delabole, Cornwall, building stone and Caithness flags. 

 Outcrops are found in the Orkneys and Shetland^, Hereford, 

 Devonshire, Caithness and Forfar. 



Shales with limestones yielding flags, building stone and lime. 

 The rocks are found at Ludlow, Wenlock, Llandovery. in the 

 Pentland Hilis. 



Limestones and shales yielding lime, phosphorite, jasper, oil- 

 stone and slates. Outcrops occur at Bala, Llandeilc, Arenig, in 

 the Lake Pistrict, Lowther and Lead Hills. 



Shales with sandstone and slates, yielding marble, flags, 

 building stone, road-metal and slates. The rock is found at 

 Tremadoc, Skye, Malvern, Harlech, Wexford, in the Lake 

 District and in the Isle of Man. 



Mainly igneous without fossils, supplying road-metal and stone 

 for local building purposes. The rock is found in North Scot- 

 land, the Hebrides, Donegal, Charnwood Forest and the Wrekin. 



c <f> 

 z! j- * 



= rt" 1 - 1 



Diagram indicating the geological progression in the earth crust of the British Isles, from the Azoic, or lifeless, to the 



Caenozoic, or recent and existing, age. The rock sequence here shown is representative of the world, except for three 



systems which do not occur in Britain, but are shown blank in their proper positions 



GEOLOGY: THE SEQUENCE OF THE ROCK SYSTEMS 



2D 4 



