How does oil shale form
Shale forms from the pressure of layers of sediment compressing bits of silt that settle into the clay on the bottom of bodies of water. The compressed clay and silt become shale over time. Shale is a sedimentary rock. Shale starts with bits of rock that erode off of larger rocks from contact with moving water and the weather. Very fine particles of feldspar, quartz, mica, pyrite and other minerals settle to the bottom of still bodies of water, such as swamplands, deep parts of the ocean and Shale oil is a high-quality crude oil that lies between layers of shale rock, impermeable mudstone, or siltstone. Oil companies produce shale oil by fracturing the layers of rock that contain the layers of oil. Don't confuse shale oil with oil shale. That is rock suffused with kerogen, a precursor to oil.