Rock Solid

November 1, 2020

As a child, I lived in Essex, in the part of England called East Anglia, which had been scoured almost flat by glaciers millennia before my ancestors moved there. Accordingly, the landscape wasn’t exciting, and when I saw pictures of mountains or even just rocky outcrops, I was intrigued. I would tell my parents I wanted “to see a rock,” but they couldn’t seem to grasp what I meant. 

Today, I live in the Trans-Mexican Volcanic Belt, the landscapes of which have been heaved up by eruptions, magma movements and other seismic events over millions of years. I’m almost never out of sight of bare rock on a cliff-face or of a fallen boulder close to a roadway. On my walks, I’ve found fossilised corals impressed in sedimentary rocks from an ancient seabed, lifted up long ago by geological action. I once brought a large sample home as a garden ornament: alas, in my absence for three years, it was used for mundane purposes, and much of the coral pattern is now worn off. 

There are still trace impressions of ancient coral on this rock I found.

The actual volcanic rock around here is a highly viscous lava, which when it erupted trapped many small pockets of gas (vesicles is the correct term). Today, these give the rock a spongy look, though of course it’s brittle, not soft.

During my aforementioned absence, somebody planned to build a house beside mine, and had a mound of rocks delivered for construction purposes. However, they lost interest or ran out of cash, so the pile became a haven for wildlife. For a time, there was a colony of squirrels in there. Today, it might be home to snakes or crawling critters of various kinds, so it’s left alone. 

Now, when I drive out of our garage, I need to reverse then make a half-turn. I often use a flat patch of ground just below the rock-pile for this. However, two weeks ago one of the rocks fell, and effectively blocked me from doing this. I tried moving it, but several efforts only shifted it a foot or so the side. It probably weighs as much as I do, and I couldn’t move it more than that.

The errant rock. It might look innocuous to you, but you didn’t try lifiting it like I did.

This reminded me how much we use rock here in central Mexico. The walls of this property are made from it, as are those of many other houses. The roadway up from the street consists of rock set in cement, and that’s survived ten rainy seasons without deterioration.

In many other places, brick is a more usual facing or structural material for a building. Even here, cinderblock is popular as a cheap means to construct a house. But inevitably, basic rock shows up at some point, even if it’s only in the paving of the street outside.

The downstairs wall of the house and the roadway outside, are made of cement-set volcanic rock.

This has been the case for thousands of years. Lava rock especially, while it’s heavy, can be chipped and shaped. Pyramidal and stepped-level remains from preHispanic cultures use it, sometimes on a grand scale. Farmers employ it to build loose walls that demarcate their fields, and sometimes, low remnant walls are a sign of an ancient perimeter for a sacred enclosure. The sense of continuity between then and today’s construction is part of the appeal of life in this area.

What always strikes me, though, is the problem I had in shifting the fallen rock: the stuff is heavy. I’ve seen rocks placed on a hillside that weigh well over a ton, yet farmers were able to shift them with the aid of their sons or neighbours. Rock know-how is something that has persisted down through the ages. And rocks are a surprisingly common component of economics in the construction industry. 

My conclusion? Just that it’s so easy to overlook something that isn’t manufactured. Until I came here, anything not man-made always seemed like a lazy short-cut. But some knowledge is passed down through the generations without anyone really noticing that it’s ancient. I don’t know how ecologically sound it is to move loads of rock around on diesel trucks, but the stuff is certainly durable, and connects a building to its underlying environment.

Still, I wish I could figure out how to move the reversing-space boulder. I suppose I could pay a couple of neighbours to lift and roll it. But now that it’s made me reflect to much on how the substrate of the ground here is used to much and so effectively, that almost feels like ingratitude. After all, my very young self asked for rocks: I shouldn’t complain that he finally came to them.

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