The Mother Lode mountain is located in the Cascade Mountain range in northern Oregon. The Mother Lode may also refer to a large region of gold deposits in the Sierra Nevada mountains.
The California Mother Lode is a narrow strip of land running through El Dorado County, Amador County, Calavaras County, Tuolume County and Mariposa County. The term came into use during the California Gold Rush of the 1840s and 1850s. The gold veins in the region were formed by the movement of the underlying tectonic plates over a period of 200 million years. The molten rock containing the gold cooled to form parts of the Sierra Nevada.