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| Marine shales of Late Cretaceous-age (mostly Moreno Formation, about 80 to 65 million years old) along Worthan Creek Canyon-southwest of Coalinga in Fresno County. Shale is highly susceptible to landsliding because of its soft physical character and because it weathers into clay (the material of which it originally formed). Note that little plant cover becomes established on the talus slopes below the high cliffs. Note that shale slopes are not blocky because shale typically weathers into small flakes and mud. This is in part to the arid summer climate and lack of water-retaining soil on the slope, and the high degree of erosion that takes place during infrequent, but often intense, storms. |
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