A Little Landsat Tour

This is an alluvial diamond mine. In the region, this one in particular has a reputation for richness, and today the machinery is sorting through the waste of earlier, less efficient mining operations.

This is slash and burn, also called queimadas or swidden – a subsistence farming practice that supports roughly 400,000,000 people on nutrient-poor soils. It yields diminishing returns: in most places, a given patch can only be burnt a few times before it’s less productive than it started.

This road is the northern border of a national park. The park is mainly grassland, and large parts of it flood every year.

Its convex outlines suggest that the greener vegetation is expanding here.

This region is a thick network of small river valleys.

Here is a reaction-diffusion pattern of vegetation, fire, and water. The land is getting dryer as we go south.

Rivers on flat plains tend to meander, or twist, as their faster-flowing outer edges undermine their banks and the mud falls out of the slower water on the inner side. When the river short-circuits and a meander breaks off, it’s called an oxbow lake or a billabong. On the south shore here are some squared fields.

It’s even dryer here, and people have concentrated near the river. The circular fields are center-pivot irrigation: a huge sprinkler arm sweeps around them. The black and white diagonal line is an image seam that I didn’t bother to fix.

I love these patterns – not ripples, not grids, not networks.

Now we are in a desert.

This pattern is typical of heavy ranching. The bare tropical soil is lighter than the scrub vegetation, and the animals tend to graze more nearer their water supply.

The pale blotches are pans, or dry lakes. In some areas, they might flood for only a few days a year. Rainwater collects water-soluable minerals, especially salts, and then evaporates, leaving them in the pans.

More grazing patterns.

Gosh, look at this.

I suppose Mars will look like this when it has roads.

This was a volcano that exploded like Mount Saint Helens long before the dinosaurs died out. Except birds, obviously.

It’s very dry here, but the landscape owes everything to water: cañons, dendritic drainage, alluvial fans.

This whole swath is color-corrected the same way. If I’d done each part alone, I might have thought the contrast was too low back where we started with the swidden fires, and I might have thought this was too harsh. But they’re the same day with the same instrument.

This too is a diamond mine, and the ocean.