Tread Gently

There is a bit of chatter about sinkholes, because of the one that suddenly appeared on a fairly new housing development in Surrey. A cynical part of me thinks that this kind of story gets bigger the closer it is to centeal London. Courtesy of a podcast, I discovered that no-one has been killed in UK as a result of a sinkhole since the middle of last century. That must be cold comfort to the people in Godstone, wondering who will fix it and when, whether it is safe to go to bed at night, and how they will ever insure, sell or mortgage their homes

Sinkholes occur naturally but, especially in UK, human activity is at the heart of many of them. There is so much we have taken out of the ground over the centuries and, once we have dug a hole and finished with it, we tend to cap over it, not fill it in. I haven't done any systematic research, but it is so easy to think of a long list of things we have taken: coal; stone; sand and gravel; flint; ores of iron, tin, arsenic, copper, lead; china clay; slate; gold and silver; salt. I have just read that even now we have a large, active potash mine under the North York Moors. I'm sure there are others, and of course we also take ground water out of aquifers

Climate change, wetter weather, more rise and fall in ground water, land use change - all create more erosion of layers of soil or rock that overlies the cavities we have left, so the chance of a sudden surface collapse increases. Now that the chances of an asteroid solving the democratic world's Problem has receded, it's some comfort to think that the chances the ground may open and swallow him up are increasing. Any chance he might visit Brazil?

I took my picture hoping to illustrate the rain-sodden state of the ground in our valley - we returned from our walk around fields and lanes bespattered. Instead, the focus on the husk of the sunflower looks oddly like a rapier, impaled in the ground, probing for cracks