This memoir describes the bedrock geology of the mountainous country lying between upper Deeside and upper Glen Clova in north-east Scotland (1:50,000 geological sheet 65E (Scotland)). The greater part of the Balmoral estate lies in this district, and the large granite/diorite mass of Lochnagar dominates the country, which is popular with climbers and walkers and immortalised in verse by Lord Byron.

The district described in this geological memoir (1:50 000 geological sheet 56W together with adjacent parts of sheets 55E, 65W and 64E) stretches from the rolling rich agricultural land around Blairgowrie to the mountainous upper parts of Isla, Shee and Fearnach glens. It straddles the Highland Boundary Fault Zone, forming the regional boundary between the late Proterozoic Dalradian Supergroup of the Grampian Highlands and the Palaeozoic rocks of the Scottish Midland Valley.