Walking the Wall

Things of stone and wood?

The latest mystery to bewilder us on our Great Wall journey – apart from old standbys like “Can anything else happen to delay us?” “When are we getting there?” and “Whose idea was this in the first place?” – comes from the field of natural history.

The question came up as we were walking in a valley near the village of Shentangyu. The day before we’d been forced off the wall by a cliff we couldn’t get around, and were taking a farmers’ trail through some orchards on what we hoped would be (and mercifully, unusually was) a short detour back to our planned route.

As we were walking, we started to notice that whenever our walking sticks hit the “rocks” below, they made a soft thud rather than the usual annoying clacking sound.

“Does this feel like stone to you?” Brendan asked as he tapped the ground with my walking pole.

I did the same. The ground looked like stone but actually felt soft. When we tapped on it with our sticks, it crumbled easily, like a wet log.

We walked up a bit further, tapping at the ground.

“I don’t think this is stone,” Brendan said. “It’s soft all the way up here (tap tap), and here (tap), and here (tap).”

We began to think that what we were standing on was not rock, or not entirely rock, but what seemed to be the remains of an enormous – and I mean enormous – tree. And not just one, but all over this orchard we noticed these “trees.”

Conducting an examination

You can get a sense of the scale by comparing the log to the full-sized tree in the background

There was no sign of branches or roots on the trees, but then they were clearly very, very old and the smaller limbs had probably just rotted away. In other respects they looked just like fallen, hollowed out logs. They were rounded, had probably been four or five metres in diametre when whole, and were long and straight. The logs had a clearly distinguishable grain, and in most places their texture was soft and crumbly, like rotting wood.

This log was quite soft

The fluting and rounded edges of this piece reminded me of old redwood logs in Northern California

But as we looked further, we saw that in other places the logs were more like stones, hard and resistant to crumbling. With the assistance of our trusty Unsolved Mysteries magnifying glass, we could see that at least parts of our logs had mineralised, i.e. they were most definitely rocks.

This piece has broken apart in a very rockish way

The white portion is definitely mineral

As we found more and more of these odd rockish logs and treeish stones, we came to the conclusion that what we were looking at were neither rotting logs nor petrified trees, but an ancient forest that was actually in the process of petrifying.

Here the wood grain is distinct, but you can also see what look like flecks of rock

This piece defies categorisation, by us at least

Unfortunately, neither of us has any geological, botanical or paleontological training, and we both have a penchant for making things up, or at least coming up with glamourous theories for our little humdrum discoveries. So we don’t really know if we found a petrifying forest, or just have overactive imaginations. We did a little internet research, and though we did find that there are several geological parks in the area featuring petrified wood, we weren’t able to find anything that would let us know what we’d seen.

If you have any geological expertise, or know someone who does, have a look at these photos or put us in touch with your rockhound friends. If we can’t find someone who can tell us whether we were looking at wood or stone, or both, whether we’ve found an ancient petrifying forest will have to remain another Unsolved Mystery of the Great Wall.

We’d like to thank everyone who has helped us with the other mysteries we’ve published, and particularly those who left enjoyable and insightful comments on our post on The Valley of a Hundred Fengsui. Simon, it was great to hear a perspective from someone with a military background, and your suggestions strike us as quite likely – we’ve read of wall in the eastern brick portion being designed to create interlocking fields of fire, so that would seem logical in the west as well; and yes , the valley is an important thruway to Datong. Jim, to hear from you is a welcome blast from the past for me (Brendan), and thanks for an interesting parallel from North America. Marg, welcome aboard, and we have read that particular numbers of signals sent from individual towers could indicate approaching troop strength, so it seems quite possible that signals from multiple towers could perform a similar function.

Looks like we’ll have to get those fridge magnets made up!