GEOLOGY MAP. CHURCH STRETTON, SHEET 166, 1:63,360
Scale: 1 inch = 1 mile
Shropshire Archives ref: 8990
Geology maps are over-printed onto Ordnance Survey maps at various scales, which can help to locate the geological outcrops in the field. As well as information on rocks and superficial deposits, they can be used to deduce information on soil types, engineering properties of the ground, potential extent of aggregates and mineral deposits and possibly ground water conditions.
The map illustrated here is a pre-metric edition, dated 1952, at a scale of 1 inch to the mile. The map itself takes up about half the sheet. On either side are important keys to the colours, shown as columns through the geological eras. There is also an index to the symbols indicating dip of the strata, cleavage planes, geological boundaries, boreholes and mine shafts. At the bottom of the sheet are horizontal cross sections which provide additional information on faulting and the relationships of the various rocks. The map is striking because of the colours. The ranges of blue depicting the Silurian (e.g. Wenlock Edge) go from north-east to south-west across the map. To the north-west are the brown shades of the Pre-Cambrian and to the south-east the oranges of the Old Red Sandstone. Throughout there are numerous faults and intrusive igneous rocks. This particular map is described as a drift sheet, which means it depicts unconsolidated glacial and fluvial deposits as well as solid rocks. This gives a good picture of ‘under-foot’ geology, though the map also shows the boundaries of rock formations at a deeper level.
At Shropshire Archives we have a good collection of 1 inch maps for Shropshire and surrounding areas issued in the 1850s and in two later revisions. The new metric edition coincides with the national grid, though often the content has not been revised. The geological memoirs to accompany the maps, published in the 1930s, are on the open Reading Room bookshelves, ref C 15. We also have recent copies at a scale of 1:25,000 for areas of particular geological interest, such as Church Stretton and Telford, and some at a scale of 6 inches to a mile, an edition that was completed in 1929.