The Ice Age impacts on the Ancient River Gravels of Windyhills

What you see before you here is a shallow dell which, depending on the time of year, may or may not have a trickle of water running along it. As you walk around the woods at Windyhills, you will probably come across a number of these little valleys. They are very similar to each other, all being no more than a metre or two deep, show a relatively straight course, and lead across the white-stone gravels (deposited in an ancient river bed millions of years ago) in a generally south-easterly direction. If you follow the course of any of the dells towards the north-west, it will rise gently almost until you reach the northern side of the gravel ridge.

Why are these dells here, and why do they all lead across the Windyhills ridge rather than along the former river course marked out by those white stone gravels?

The answer to these questions relates to events during the last Ice Age, more than 15,000 years ago. The area around Windyhills has been covered by ice at least once (and probably many more times) during various glacial episodes over the past 800,000 years or so. At one stage during the last glaciation to affect the area, ice moving over the landscape from the north-west came to a halt more or less along the northern flank of the Windyhills gravel ridge. The position it halted at is revealed by the steep slope on that side of the ridge (see the illustrations in the panel on the information board). As the climate warmed towards the end of the ice age, more and more water was produced by melting of the glacier. That water was originally ponded up between the ice edge and the northward slope of the Windhills ridge, but as the ponds filled, eventually they would have spilled over the crest of the ridge, and the water then flowed across the gravels towards the ice-free lower ground to the south. As this water flowed across the gravels it cut away the pebbly ground to form various dells, such as the one in front of you just now. You are standing on the edge of a feature which has survived in this area for well over 10,000 years, a remnant of an ancient landscape.