Earth is the only planet in the solar system having a well developed continental crust. About 4.54 billion years ago Earth accreted from the collision of numerous small planetesimals within only 50 to 100 million years. Later, an object the size of Mars collided with Earth forming the moon. This caused young Earth to melt entirely, destroying a primary cooling crust of feldspar, leaving behind Australia's 4,4 billion years old zircon minerals. After recooling Earth developed a secondary crust from lava flows of molten mantle material caused by heat release from radioactive elements. These days, Earth’s interior was hotter leading to increased plate tectonics. More then 100 small basaltic plates drifted around and collided with each other compared to a mere dozen large plates today. Colliding being still young hot and hydrous the subduction caused the diving plates to melt at comparably shallow depths forming first felsic magmas called tonalite trondhjemite granodirites, or the TTG suite. This tertiary crust formed the first continental cratons on Earth. These 2.5 billion years old sediments of Waterton Glacier contain zircons as old as 3.96 billion years.
Canon 20D, Canon EF-S 10-22mm, f/22, 2 sec, ISO 100, tripod