The Colorful Painted Hills in Oregon

Oregon’s Painted Hills, part of the John Day Fossil Beds National Monument, are a geological marvel in the high desert of central Oregon, roughly 10 miles northwest of Mitchell. Their vibrant, layered bands of red, yellow, orange, and black are a striking testament to millions of years of Earth’s history, shaped by volcanic activity, climate shifts, and fossil-rich sediment deposition.

Layers of colored rock and soil at the Colorful Painted Hills, Oregon
Layers of colored rock and soil at the Colorful Painted Hills, Oregon.
You might be confused the first time you see these colorful hills. But calm down, you’re not stuck in a landscape painting – you’re just in Wheeler County, Oregon’s Painted Hills, a unit in John Day Fossil Beds National Monument.

The hills aren’t painted on purpose. It’s a product of nature that has been through various geological eras, formed 35 million years ago. This was just a river plain that gradually sculpted and airbrushed into layers of ash filling the place with splashes of colors, thanks to ancient eruptions. Now see each colored-layer composed by different minerals: lignite for black; mudstone, siltstone and shale for gray; and laterite soil for red and orange.

the Colorful Painted Hills, Oregon

Geological Formation

The Painted Hills belong to the John Day Formation, a sequence of sedimentary and volcanic rocks spanning from about 54 to 6 million years ago (Paleocene to Miocene). The hills themselves primarily date to the Eocene and Oligocene epochs (roughly 39–20 million years ago). Their colorful layers result from:

Volcanic Ash Deposits: The region was blanketed by ash from Cascades volcanic eruptions, notably from the Western Cascades and later the High Cascades. These ashfalls, rich in silica and other minerals, compacted into tuff and claystone layers.

Paleosols (Ancient Soils): The vivid colors reflect paleosols formed under varying climatic conditions. Red bands, rich in iron oxides (hematite), indicate oxidized, well-drained soils from drier periods. Yellow and orange hues, often from goethite, suggest wetter, less oxidized environments. Black or gray layers point to organic-rich or waterlogged soils.

Claystone and Siltstone: The fine-grained sediments, derived from weathered volcanic ash and eroded rocks, are highly susceptible to erosion, sculpting the hills’ smooth, rounded shapes.

Fossil-Bearing Layers: The formation is renowned for its fossils, including plants (e.g., dawn redwood), mammals (e.g., early horses, camels, and rhinos), and invertebrates, preserving a record of Cenozoic ecosystems.

The colors shift with moisture and light—wet conditions deepen the hues, while dry weather mutes them. This dynamic visual effect is due to the clay-rich soils absorbing and reflecting water differently.

Colorful Painted Hills landscape in Oregon

Visiting and Preservation

The Painted Hills are accessible year-round, though spring and fall offer milder weather and vivid colors. Key trails include:

Painted Hills Overlook Trail (0.5 miles): Panoramic views of the main hills.

Carroll Rim Trail (1.6 miles): Higher vantage point for broader context.

Leaf Fossil Hill Trail (0.25 miles): Showcases plant fossils.

The site is protected; visitors must stay on trails to prevent erosion and preserve fragile fossils. Off-trail hiking or collecting rocks/fossils is prohibited.

Colorful Painted Hills landscape in Oregon

Fun Facts

  • The hills’ colors inspired their name, first coined by early settlers in the 19th century.
  • Fossils from the John Day Formation have helped paleontologists reconstruct North America’s post-dinosaur ecosystems.
  • The area’s remoteness and lack of light pollution make it a stellar spot for stargazing.
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