Zhangye Danxia

Start here with the single fact that explains everything else you’ll see: the colored bands run at a slant, not level. That slant is the whole story. Every one of these layers was laid down flat, sand and mud settling at the bottom of ancient water — flat is how sediment always settles. So when you look across these hills and see the stripes climbing diagonally up one slope and down the next, you are looking at layers that were tilted long after they turned to stone, heaved out of level as the mountains to the south rose and dragged the whole region up with them. The angle you see is the exact angle of that tilt. It is also why you can see so many layers at once: on flat-lying rock you would only see the top one, like the cover of a closed book. Tilted, the book lies open, and every page shows its edge.

This is the highest of the boardwalk viewpoints, and the one to come to for the long view. From up here the individual hills stop reading as separate mounds and start reading as what they are: one thick stack of layered rock, sliced into ridges by erosion but originally continuous, every ridge sharing the same bands in the same order. That order is the point. In undisturbed layered rock the oldest material sits at the bottom, and each layer above it is younger than the one beneath — a plain rule that turns a striped hillside into a timeline you can read from the ground. Here, with so much of the sequence in view at once, you can trace a single distinctive band — a bold red one, say, or a pale creamy seam — across ridge after ridge and watch it hold its place in the stack every time. The colors are not laid on the surface. They go all the way through, one whole layer at a time.

The name points at the colors, and this is a good place to ask where they come from. The short answer is iron, mostly one metal doing different things. Iron is scattered all through this sediment, and its color depends on the air and water it met as the mud turned to stone. Where iron oxidized — met oxygen and rusted — it stained the rock the reds and rich oranges that dominate here. Where it stayed buried, starved of oxygen, it held greens and greys instead. Traces of other minerals tint the paler creams and yellows. So each band’s color is really a record of the conditions in that particular layer when it formed: a wetter spell, a drier one, a stretch with more oxygen reaching down or less. Read that way, the stripes are not just pretty. They are a strip of climate history, each color a different chapter in how this basin filled.

By now you’ve read what the layers are and why they’re colored. This viewpoint is a good place to watch what’s taking them apart. Look at the slopes and you’ll see they aren’t smooth — they’re combed top to bottom with narrow gullies and sharp little ridges, all running straight downhill. That texture is the work of water, and specifically of rare, heavy rain. This is dry country; rain comes seldom, but when it comes it comes hard, and with almost no plants to slow it, it sheets straight down the bare rock, cutting the same downhill grooves a little deeper each time. Softer bands wear back faster and become the gullies; harder bands stand out as the ridges between them. The whole carved, fluted surface that makes these hills so distinctive is younger than you’d guess — not the deep past of the layers themselves, but the ongoing present, still being shaped by the next storm.

The colored ridges are only half of what this region’s rock does. Come to Binggou, a separate scenic area over the next valley to the west, and the Danxia rock takes a completely different shape: instead of smooth, low, brightly banded slopes, here it stands up in cliffs, spires, and blocky forms that people have long compared to castles and city walls. The rock is close kin to the colored beds, the same broad family of red-bed sandstone, but harder and more thickly bedded — so where the softer colored layers erode into rounded stripes, this stiffer rock breaks along vertical cracks and keeps its height, weathering into towers rather than ridges. The color here is quieter, mostly greys and ochres rather than the reds next door. Seeing both in one trip is the real lesson of the place: same rough age, same dry-country erosion, but the shape the land takes depends entirely on how hard the particular rock is and how it’s stacked.