By: Blonde Two

Last Sunday (you know the one, biting wind, nearly snowing, slight hangover) I went for a walk with a friend on Dartmoor (what better way to spend time with a friend). We walked on a known track for a while then decided to turn our route into a circular one by cutting uphill across a piece of open moorland.

Dartmoor’s North Hessary Tor

It was a good decision. We followed a line of boundary posts up towards the North Pole (otherwise known as the North Hessary Tor transmitter mast), stopping to say ‘hello’ to each one as we went. It was interesting to note afterwards that these particular posts aren’t marked on the Ordnance Survey map. This isn’t uncommon on Dartmoor but the boundary markers are a really important part of the moor’s history, and make great navigation features (especially the ones that aren’t there!) We Blondes are particularly fond of them.

We are also fond of the North Hessary Tor mast. You can see it from all sorts of surprising Dartmoor locations, and even at night it makes a great ‘welcome home’ after a long walk. One this particularly walk however, it wasn’t the boundary posts or the mast that really caught my eye. It was this rather uninspiring hole in the ground.

Map – copyright Ordnance Survey 2021

Dartmoor’s peat bogs

It’s not very impressive is it? A hole in the peat with straight sides at the top, falling away into a small patch of boggy ground below. Except that this hole tells a story. The sort of story that anyone exploring this landscape might want to hear.

Especially on a rainy day.

Take a look at the map snippet (thanks OS Maps). Those brown lines are contour lines. Each joins up points that are at the same level above sea level (in this case between 450 and 500 metres). The little bumps in the contour lines show where the land dips, they are called re-entrants. Point of interest here, these bumps point up the hill, if they pointed downhill, they would show raised areas, and be called spurs.

Interesting navigation features

On a relatively flat landscape such as Dartmoor, re-entrants can be difficult to spot. If you look closely at the photo (facing south-ish), you’ll see the dip continuing back down the hill, where it eventually becomes a stream. Continuing up the hill, past the last contour line bump, you’ll see a pool marked. In all likelihood, this is where a spring rises.

The bog then stream that flows down this hill through my little pool, eventually joins the River Walkham, which eventually joins the River Tavy, which eventually joins the River Tamar, which marks the border between Devon and Cornwall, over which my Dad likes to smuggle proper farm baked Cornish pasties.

So it’s a far more important pool than even I first thought it was.

Some sound navigation advice

Why is this all important to the walker and budding navigator? Well if you’ve ever fallen in a Dartmoor bog on a winter night, you’ll know the answer to that!