Horsham Steps after the Rain

According to statistics from the UK’s Meterological Office, March 2023 was the wettest March in England since 1981, and the third wettest on record, with over twice the average monthly rainfall.

The last few days of March were particularly wet on Dartmoor, with intense rainfall over short periods leading to rapid increases in the water level of most rivers coming off the Moor. As a result, I decided to re-visit Horsham Steps to catch some more dramatic images of the River Bovey in full spate as it flows over Horsham Steps following my earlier visit earlier in January, (see Image of the Month for January 2023). The Steps are best seen from the south (Manaton) side of the river, looking upstream.

The ‘Steps’ are actually a series of granite boulders blocking the river, but used as a footpath to cross from one bank to the other. In summer months especially when river levels are low and for most of the rest of the year, the route across the boulders is not too much of a scramble, but when the river levels are high or in wet weather when the boulders are wet and slippery, the route across the boulders requires care.

The river can still be crossed with caution when the levels are not too high, as I foolishly did on New Year’s Eve 2013… it was tricky and not to be recommended, but anything to get the best camera angle!

In some respects the Steps are more dramatic in summer when the river levels are lower, as the immense size of the boulders forming the blockage in the narrow valley (i.e., the Cleave) and not just the river is revealed. The lush green foliage of the temperate rain forest environment of the Cleave can give a quite exotic ‘jungle’ atmosphere. Amazingly though the Steps are not a barrier to fish migrating upstream – salmon, trout, seatrout all migrate upriver to spawn beyond the Steps.

A Google search plus my collection of Dartmoor literature doesn’t reveal much about the formation of Horsham Steps, though I suspect they arose as part of ancient rockfalls nearby along with clitter from the steep-sided flanks of the valley, and became rounded by the action of other smaller boulders and pebbles and general water erosion travelling down the river in times of spate, although perhaps they could also have some sort of glacial outwash or terminal moraine origin. At least that seems (to me) to be the most simple and logical explanation.

The River Bovey is situated on the Bovey arm of the Sticklepath Fault, a Northnorthwest-Southsoutheast trending strike-slip fault trend running along an axis across Devon from Lundy Island to Bideford Bay, thence to Torbay via Hatherleigh, the village of Sticklepath near Okehampton, Lustleigh Cleave, and Newton Abbot. Across Dartmoor where it is best observed topographically, it consists of two parallel faults in a compound fault zone, that give rise to the Wray Valley and the adjacent Bovey Valley, where it is perhaps at it’s most dramatic where it passes through the steep sided narrow valley of Lustleigh Cleave.

Without going into the finer points of structural geology, faults are rarely just a single linear feature. Horsham Steps are located at a dogleg on the River Bovey, suggestive perhaps of two parallel fault traces with a lateral offset, the dogleg forming a natural constriction for the granite boulders as the river switches from one dominant fault to the other, also perhaps explaining the local drop in elevation of the river.

The Lustleigh Clam Bridge (or Tree trunk bridge) as it locally known is an old crossing of the River Bovey, between Manaton and Lustleigh that has been there since at least 1888. Clam bridges are simple bridges made of timber – usually old tree trunks – that were once a common sight in the wooded valleys around the fringes of the High Moor. There was quite an uproar locally in 2007 when the health and safety brigade decided that in order to avoid potential lawsuits, traditional clam bridges should be replaced with sturdier more conventional wooden bridges… Fortunately the decision was reversed, although not before a more modern conventional footbridge was built for those inclined to dyspraxia some 10 yards downstream from the clam bridge.