A New History of Aberdeenshire, Alexander Smith (Ed), 1875
The parish derives its name from the Gaelic, Glas, which signifies grey, and as it is variegated by a number of grey and green hills, the name is very appropriate. The Gaelic and the English are pronounced alike.
It is bounded on the north by the parish of Cairnie; on the east by the parish of Huntly; on the south by the upper portion of the parish which lies in Banffshire; and on the west by the parishes of Mortlach and Botriphnie, also in Banffshire.
The greatest breadth of the parish, in a direct line, from the source of the Gordon's burn, in Huntly, to the Ardonald Hills, in Cairnie, is nearly four miles; and the greatest length, from east to west, also in a direct line, is a little over five miles. The whole area in Aberdeenshire is estimated at 8,920 acres.
The parish is intersected from south to north by the Doveran, which runs in a deep valley throughout. The hills of Aswanley and of Parks, east of the river, rising to a considerable elevation toward the braes of Gartly boundary; while those on the west of the Doveran rise from the valley of the river, and the southern bounding stream of Glenmarkie into the high western ridges of Grassmaul, or Corsemail, bounding with Mortlach, and to the northern bounding hills of Ardonald, which form a continuation of the ridge running westwards from the Beinn Hill in Cairnie to the hills of Drummuir, in Botriphnie. The highest point on this range being 1,000 feet above sea level. The lowermost point in the parish on the Doveran, at the burn of Artloch, is about 530 feet; and the highest point at Park of Aswanley, is 615 feet above sea level. The tops of the higher hills are rocky and rugged, and are covered with heath, interspersed with stripes of coarse grass. The lower uncultivated hill slopes are also rugged, but covered with finer grasses, natural birch, and juniper bushes, with birch and alder trees along the valley of the river.
[A New History of Aberdeenshire, Alexander Smith (Ed), 1875]