Geoscience Reference
In-Depth Information
FIG
230.
Main drainage valleys and coastal flooding zone in Area 13.
Landscape A: Jurassic limestone hills
Landscape A extends across the northwestern part of Area 13, from the northern edge
of Milton Keynes, via Northampton to Rushden. It is underlain by bedrock ranging
from Triassic to Middle Jurassic in age, though the Middle Jurassic limestones provide
most of its distinctive hill scenery. It is drained by the River Nene, which has a mean
flow of only 1.3 m
3
/s near the western edge of Area 13, but then increases in flow
northeastwards as its tributaries converge and it enters the Fens in Area 15. Large
gravel workings from Northampton downstream reflect the Nene's much greater activ-
ity during the Ice Age, when its spring melt flow rate was sufficient to deposit large
floodplains of gravel.
