Index Maps for England & Wales Quarter Inch
1889 - OS General Map
From 1889, the quarter inch geological Index Map edition was published using the OS General Map of England and Wales as a base map laid out in 15 sheets. They were issued as hand-coloured sheets from 1889-96, in printed colour in 1896-97 which were revised and issued from 1901-05. This map series was designed to be assembled as a wall map; the blank sheets 1 and 3 were reserved for the title block and 'The Index of Colours' (legend), respectively.
1907 - First edition
From 1907-10, the geology was published on a revised layout called the First Edition Quarter Inch Map of England and Wales (despite the earlier edition). This layout had 25 numbered sheets but, by combining some numbers, was issued in 20 actual sheets. This layout went through four editions with partial revisions in 1921-22 and 1928-40. The post-war fourth edition (1951-1969) had the National Grid imposed in 10km cells. Reprints continued to at least 1970.
1977 - 1:250,000 UTM
In 1977 a new 1:250,000 UTM (universal transverse mercator) series was initiated which covereds all of the UK and adjacent continental shelf. Each sheet is 2°longitude x1°latitude and referenced by the coordinates of its southwest corner. Thanks to David Archer for permission to use his layout maps as published in Hellyer, R., ‘Ordnance Survey Small-Scale Maps Indexes: 1801-1998, publ. David Archer, Kerry, 1999.
1858 - GSEW Wales sheets
Prior to these full editions on OS base maps, The GSEW began its own quarter inch series in 1858. It was intended to cover all of England and Wales on sheets numbered southwest to northeast. It uses a numbering system evidently for all of England and Wales and therefore apparently laid out with reference to the OS. The maps show the sheet lines and numbers for the Old Series one inch maps. Only the maps for Wales were ever produced and these only as geological maps, not topographic. It is evident that the intention was to produce this as a national series but no index map for the whole of England and Wales has been discovered for this false start. Maps of this series are rare as the edition was aborted and production was limited. Only sheet no. 10 was issued as a revised edition in 1874.