Friends of Coombe Wood

The Geology and Topography of Coombe Wood, and the Climatic Environment

Much of the information on the geology and climate of the wood is found in the book by Oliver Rackham: The Ancient Woodlands of England: The Woods of South-East Essex, published in 1986 by Rochford Borough Council.

Rackham describes the topography as “sloping down from a plateau in the south to the valley of a stream along the NW boundary. Within the wood is a second (very steep) valley – almost a ravine.” Although the stream in the north-west carries water most – if not all – of the year, the stream from the pond is very seasonal and will depend on the recent rainfall.

This description does not encompass the woodland to the north-west of the stream, which is part of the current woodland.

To the casual visitor seeing the wood from the Bread and Cheese Hill, this slope is very obvious. However, it does not describe the distinct mound – known as Coombe Kop – close to the southern boundary, with steep slopes up to it from the lower, western parts.

These lower parts are underlain by London Clay (deposited around 60–70 million years ago). The upper parts are underlain by the Claygate Beds (alternating strata of sands and clays) lying on top of the London Clay. The whole area was subsequently covered by a dense layer of loesse in the late ice age. It is this loesse which largely determines the soil of much of the wood.

The Topography and Streams of the Wood

The main surface features of the wood are determined by the slope. This slope can clearly be seen along the southern boundary, by the London Road (A13). The lowest parts on this boundary are at the south-western corner, at the junction with Rhoda Road Northeast at around 47m above sea level. The road slopes up to around 75m at the eastern edge of the wood.

Walking along this southern boundary from Rhoda Road, the slope is at first gentle (around one in thirteen) but, once past the ride, it becomes steeper (around one in ten). Beyond Hillrest, the house about half way up, the slope becomes less until it flattens out just beyond the wood.

The slope of the ground to the north of the road (left as you go uphill) varies greatly. From Rhoda Road to the Ride entrance, the ground is slightly higher than the path. Beyond the ride, by Coombe Kop rises as a steep-sided hillock to the left. The roadside ground here slopes up to the Kop. Moving up the hill, this slope gradually reduces until, by Hillrest, it is almost flat. Beyond Hillrest, the ground is still flat, but it then begins to dip down to the left, with this dip getting steeper as you walk up the hill to the top.

This dip is the southern flank of a steep-sided valley, with Lake Drive on the far side. Within the valley, there are several small streams converging into a pond. This pond has been formed by the damming of the stream. In recent years, this dam has been partially breached, so that the water level in the pond in now nearly a metre below the level it once was. Upstream from the pond, the wood narrows, and the ground tends to be damp, with groundwater percolating down the slopes on either side. This provides a rich habitat for Bluebells.

Bluebell Dell

This is the floor of the valley known as Bluebell Dell because of the rich sward of Bluebells in late April and early May.

From the pond, a stream flows westwards, with relatively gentle slopes on either side except for the northern flank of Coombe Kop. As it crosses the main ride, the stream is partially dammed so that there is a marshy area just upstream from this. The stream flows underneath the ride (through a pipe) and then flows down to join the main stream, again with only gentle slopes either side. This stream is not a permanent feature. In a dry season, especially in suummer, it dries out.

The main stream flows from the north of the wood, south-westerly until it enters a culvert before reaching Rhoda Road North. The eastern side of the stream has a gentle slope, but the western side is steeper. This stream is permanent, and for much of its length flows in a steep-sided gully up to a metre or more deep. As it approaches Rhoda Road North, the gully opens out, and here the stream will flood after wet weather.

There is another stream running along the wood boundary from near the Coombewood Drive entrance, flowing westward in a gully to join the main stream.