HOOKNEY TOR & AN INFORMAL DARTMOOR LETTERBOX


Hookney Tor & Grimspound Dartmoor - Map

Hookney Tor is a windswept rocky outcrop on Dartmoor at 414m / 1358ft ASL. It watches over the Grimspound, an intriguing bronze-age circular enclosure with the remains of 24 houses, some inhabited until medieval times. It will have a post in its own right in due course. We investigated both with our granddaughter Berry last August during a short holiday together (grandparental treat!) on Dartmoor.Hound Tor 8

Hound Tor 12Hound Tor 5

After exploring the Grimspound, there is no doubt about the next achievement to tackle: a steep stony path leads invitingly from the walls to the top of the Tor. As you climb, the Grimspound quickly gets smaller below you. Hound Tor 23Hound Tor 26Hound Tor 3

Berry was not the only wild creature on the moor…Hound Tor 22

AN EXCITING DISCOVERY THAT WAS DISAPPOINTING

As we climbed, we noticed that the rocks all around were embedded with fossils. Or so we believed. We took lots of photos of these amazing calcified creatures that by some strange process were to be found at nearly 1500ft. Only later, when we did a bit of research online, did we find out the disappointing truth: not fossils, but megacrysts. The technical explanation is as follows:

The main exposure at the Tor is of megacryst granite (also known as “Giant Granite” or “Big-Feldspar Granite”). It is probably from near the roof area of the batholith. The feldpars are of perthitic orthoclase that is porphyroblastic (later replacive crystals) in origin and not phenocrysts (large crystals that have developed in the magma). In some places the southwest England granite megacrysts have been seen to develop into aplite (fine-grained quartz-feldpar veins of late origin), which is possible for porphyroblasts (developing by replacement after the veins) but not for phenocrysts (early and which should be cut through by the veins).

 Hound Tor, Dartmoor. Fossils? No, Megacrysts Hound Tor, Dartmoor. Fossils? No, Megacrysts Hound Tor, Dartmoor. Fossils? No, Megacrysts

A DISAPPOINTING DISCOVERY THAT WAS EXCITING

Tupperware at nearly 1500ft? The plastic rubbish left behind by some idle picnicker? But no… Berry spent some time exploring the crannies of the rockiest outcrops, and in the process made her next ‘Letterbox’ discovery… [The previous year’s find is HERE]

Hound Tor 6Hound Tor 13Hound Tor 20Hound Tor 30

Berry was not the first person to discover the box, which had been left by a girl from Surrey, with a message encouraging people to write in the notebook inside. This was already well-filled with the names, addresses, messages and drawings of previous explorers. There was also a strange mix of ‘souvenir’ items people had left – a car park ticket from Alton Towers, a ‘poppy day’ poppy, a couple of smoothed-out sweet wrappers, a button, and other such debris that walkers might find in their pockets… So Berry added a 1p coin, and added her contribution to the notebook. It may not have been an official Dartmoor Letterbox, but it was a lovely idea to have hidden it for others to enjoy.

Hound Tor 18Hound Tor 17Hound Tor 29Hound Tor 15Hound Tor 31

Credit: photos 4, 5, first megacryst, and all agile activity by Berry

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9 thoughts on “HOOKNEY TOR & AN INFORMAL DARTMOOR LETTERBOX

  1. Lovely, lovely post, RH! I’d love to visit Dartmoor – and it’d be great to see what inside the letterbox in a year or two. 🙂
    Thank you, Berry for all the wonderful images by and of you! This was a treat for the eyes.
    Dina x

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    1. Yes, it was v exciting. Berry filled a full page of the notebook, including a drawing of the pony she’d been riding. Huge fun. I can see feldspar is exciting too – but not as much as if they really had been fossils! RH ps your garden is looking lovely for Spring. We have a large vine across the back of the house – for various reasons I haven’t been able to prune it yet, and it may already be too late…

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      1. If you are talking grape vine – they are still pruning their vines over here and we haven’t pruned ours yet. I’m not an expert but it would not be considered late here.

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  2. I think you have your tors mixed up here – this is Hookney Tor – Hound Tor is south of Manaton…
    If you look on Wikipedia/google maps it shows the correct location of both these tors…

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