The distribution of rock types in Scotland has ensured that Scotland is able to produce good quality rock aggregate almost anywhere in the country. In general all aggregate is derived from two main sources: deposits of sand and gravel, which are almost exclusively of glacial origin, and crushed rock aggregate from quarries mining solid rock.
Scotland is self-sufficient in aggregate production (and, in fact, exports aggregates). The annual amount of crushed rock aggregate is more than twice that of sand and gravel, with a total annual production of about 33 x 106 tonnes. Figure 18.1 shows the annual production of aggregate from 1972 to 1998 (BGS 1972 et seq.) and indicates that production continued to increase (or at worst plateaued out) during the recession from 1990 to 1995, in spite of UK total production showing an overall reduction of over 20% during this period. The graph shows that the annual production of sand and gravel has fallen slightly from 12 x 106 to about 10 x 106 tonnes per annum, and that hard rock production is now more than 23 x 106 tonnes per annum. It should be emphasized that a crushed rock granite quarry at Glensanda on Loch Linnhe which started in 1987 accounts for more than 5 x 106 tonnes of the crushed rock annual production. This quarry, the first custom- designed superquarry in Scotland, sends material to southeastern England, and also to northern Europe and the United States (see below).