John Day Fossil Beds /Painted Hills of John Day Fossil Beds
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What causes the colors in the Painted Hills?

Aluminum (Al), Silicon (Si), Iron (Fe), Magnesium (Mg), Manganese (Mn), Sodium (Na) Calcium (Ca), Phosphorous (P), Titanium (Ti), Potassium (K), Oxygen (0), Hydrogen (H) The answer is complex. The original ashfall was probably a very light, buff color, comprised primarily of the above elements. Just like ingredients in a recipe, these twelve elements, plus traces of seventeen others, were mixed in a variety of ways. The various mixes produced minerals of different colors that make up the hills. Sometimes the color of one mineral dominates, such as the rust colored layers, rich in iron oxide. A blend of minerals may create a color different from the originals. The yellows are a blend of iron and magnesium oxides. Ttie black "hash-marks" are primarily colored by manganese oxide.

02-Painted Hills of John Day Fossil Beds