The continents are the visible parts of Earth's crustal plates that, like great floating puzzle pieces, get pushed around, torn, wrinkled, and recombined. In the composite satellite image of North America and the eastern Pacific Ocean, the northwestward drift of the Pacific Plate is tearing the Baja California peninsula from the Mexican mainland.

A Look at Geology: The Stone Raft
La Perspectiva de la Geología: La Balsa de Piedra

Like a stone raft, greater Baja California slowly drifts between a cool Pacific Ocean and a warm Sea of Cortés. This body of rock, comprising Baja California and Southern California, is riding on the Pacific Plate on its northwesterly journey. Soaring mountains, plunging canyons, volcanic flats, a legion of islands, the glorious gulf—all are testimony to the creative force of plate tectonics. On this isolated peninsula, almost an island, the landscapes are then reshaped by erosion and subsequent plate movement. Species adapt, giving rise to new species over thousands and millions of years.

Tajo Canyon and eastern escarpment of the Sierra de Juárez
Bill Evarts
About 100 million years ago, the clash of crustal plates along western North America melted huge amounts of rock that later hardened deep below Earth¹s surface. These great blocks were then thrust into the sky, forming the mountain backbone that runs through Southern California and most of the Baja California peninsula. The older stone on top of the uplifted mountains has eroded away, revealing the rock beneath.

Isla San Luis
John Shelton
Volcanoes can erupt by explosion or by oozing lava. This island shows examples of each.