8 SCIENTIFIC SURVEY OF ABERDEEN AND DISTRICT 
characteristic features is the alternation of close gorge and open reach which 
becomes well marked near Towie, and exercises a considerable influence 
upon the distribution of population. ‘The Towie and Kildrummy basins, 
which have been excavated out of the Old Red Sandstone, form the first 
regions suitable for settlement as we come downstream apart from the 
alluvial strips along the river and its tributaries. ‘The Kildrummy basin is 
of special interest as it provided a lowland through which passed the road 
from the western passes of the Mounth to the north by way of Huntly. 
On this important strategic route, and in a relatively fertile district, rose 
Kildrummy Castle, the largest castle in the north of Scotland. The 
Alford basin is more extensive and even more distinctive. The river 
enters and leaves it by water gaps over 1,000 ft. deep, and only at one 
other point are the surrounding uplands much below 1,000 ft. The 
basin, in the formation of which glacial erosion has played a large part, 
contains a considerable amount of good agricultural land. Lower down, 
the Don passes through the Kemnay and Kintore basins, which are, how- 
ever, less decided in character than those already mentioned. 
An important point of difference between the Dee and the Don is that 
while the Dee is well graded the Don has been rejuvenated, not by 
uplift but as a result of glacial action. The ice streaming across its valley 
filled it with gravels and boulder clay, and when the river returned 
it found itself forced in places on to harder rock, with the result that its 
gradient was changed. Hence water power is more abundant in the valley 
of the Don than in that of the Dee. On the whole, too, the valley of the 
Don is the more fertile. The fluvio-glacial soils which occupy consider- 
able areas in the valley of the Dee absorb water easily and the region often 
suffers from drought. For this reason it has been said that one day’s rain 
will do for the Don what it takes two days’ rain to do for the Dee. That 
the agricultural importance of the lower Don was considerable even in 
prehistoric times is indicated by the stone circles, which are more numerous, 
especially near Inverurie, than in other parts of the county ; the numerous 
castles of medieval times bear witness to the same fact. 
Among the more important settlements in the basin of the Don the 
following may be noted. Alford is situated in the fertile Howe of Alford, 
nearby the ford which crosses the Don, and in the central part of the 
basin ; it is only a small village, but it forms an admirable market place 
for the surrounding district, and gains by the fact that it is the terminus 
of the Donside railway. Kemnay was merely a hamlet until the opening 
of the granite quarries in the neighbourhood. Kintore is situated just 
above the remains of a great fluvio-glacial fan which must have stretched 
far across the Don valley, and just below the low ground near the river ; 
it has been a Royal burgh since the days of William the Lion. Inverurie 
is situated at the confluence of the Don and the Urie at a point where 
routes to the north must cross the Don. ‘The town is built partly on the 
lowest slopes of another great fluvio-glacial fan which must at one time 
have almost blocked the Don. The Bass of Inverurie, a severed spur of 
this fan, most of which has been destroyed, may have given the town 
some importance in early times ; in medieval days it was the site of a 
feudal castle. The modern importance of Inverurie dates from the 
