A New History of Aberdeenshire, Alexander Smith (Ed), 1875
In some old charters the name is written Bourti-ach : achadh, contracted, means the field; as to the prefix, we have no information whatever of its meaning, but from the fact of the parish being upon the borders, and within the ancient earldom of Garioch, the old spelling of which was "Garvyoch," showing its etymology is from the Gaelic "Garbh-chrioch," which signifies the rough bounds, or district, we must therefore conclude that it, has some reference to the rough lying land in the parish, of which the hill of Barra is the head, as the hill of Lawal side is the highest in the eastern "bounds" of the district.
Bourtie is bounded on the north by the parishes of Meldrum and Tarves; on the east by the parish of Udny; on the south by the parish of Keith-hall; and on the west by the parish of Daviot.
Its greatest length from north-east to south-west, measures in a direct line, about 5½ miles; and its greatest breadth from south to north, also in a direct line, measures 2½ miles; and the whole area is computed to be 5,695 acres 086 decs.
The western division of the parish is comparatively flat, but it rises with gentle slopes to the hill of Barra, which is 634 feet above sea level. The southern ridge rises at Collyhill, on the east of the Lochter burn, a tributary of the Ury, and runs eastward to the Lawal hill (773 feet), and the hills of Thornton and Kingoodie; and on the eastern side of the latter, flows the burn of that name, forming the chief affluent of the Brony water, which falls through Udny, and into the Ythan at Esslemont.
[A New History of Aberdeenshire, Alexander Smith (Ed), 1875]