One colossal continent, Pangaea, held all the land of the great planet that was Earth. A mighty, restless sea miles deep covered the remainder of the world.
Composed of granite-like slag, Pangaea existed for many millions of years. This huge crustal plate was sixty miles thick and rested upon the basalt of the deeper mantle of the globe.
The Earth was already immensely old, more than four billion years, when the one huge continent existed. It was not the first super continent to have coalesced upon the surface of the Earth, only the last.
Two hundred million years ago the hot flows of the softened rock in the Earth’s mantle, fueled and stirred by the planet’s own internal heat, boiled upward with irresistible currents. Pangaea fractured and shattered into seven giant blocks and several smaller ones. The blocks drifted apart an inch or two each year upon the dense basalt of the ocean floor.
The island continent of Australia moved south. The North American Plate that included half of the Atlantic Ocean, moved westward to collide with a section of the Pacific floor—a mass of the planet that extended to Japan and was rafting north. At the crushing contact of these two gigantic plates, the leading edge of the North American Plate was crumpled, broken, and thrust up in mighty mountain ranges. Broad, down-faulted block valleys were formed in between these ranges.
From the hot center of the globe, mineral-rich fluids and gases were pumped into the passageways of the fractures and ruptures of the mountain rocks. As the emanations migrated upward away from the source, they found regions that were cooler and had less pressure. The minerals that could not remain in solution in the new environs differentiated and precipitated out into the fissures of the mountains. The atoms of metals began to settle out of the mineral solutions to rest along the crevices within the mountain.
Time passed and billions more atoms of metal rose up from below to add their mass to the growing mineral deposit.
Finally the passageways through the rocks closed and the mineral-rich fluids ceased to flow. Left resting within the mountain were stringers and pods of a glorious yellow metal.
The mountains of the North American Plate cut crosswise the path of the prevailing storms that drove in from the west, forcing the moisture-laden winds to rise abruptly. The sky-brushing crown of the mountains, one day to be called the Sierra Nevada Mountains by a race of men, milked the clouds, wringing stupendous quantities of water from them to fall upon the land.
The water rushed down from the rocky crags of the mountains and collected into rivulets, which grew into creeks that merged to form mighty rivers. The rivers hurried west carving wide channels across the broad valley bottoms. Near their mouth, the two streams joined their prodigious currents and charged off through a deep gorge to the ocean. For countless millennia, the ancient ancestor rivers of the Sacramento and San Juan cut and eroded the mountains. The common rocks were flushed away and the yellow metal they contained was concentrated into rich deposits in the gravels of the headwaters of the two rivers.
As the Pacific Plate continued to drive north, the land near the ocean lowered. The salty brine of the sea flooded in to fill the valleys of the Sacramento and San Juan rivers for many miles up their courses. Several hills near the river were inundated until only their topmost crests poked above the water to form islands in the newly created bay.
That is the way man found the land.
He named the sunken, flooded river channels the San Francisco Bay. The deeply carved gorge leading to the sea between the peninsula headlands became the Golden Gate. The yellow metal he found in the gravels of the mountain streams, he called gold.