In the Caribbean, the heavier North American Plate is sinking below the lighter Caribbean Plate, in an area known as a subduction zone. The subduction of the North American Plate into the Earth’s mantle generates partial melting and creation of basaltic magma and gave rise to the formation of volcanic islands. As the magma accumulates in large chambers below the Earth’s surface, it changes composition and becomes more like granite. As volcanism ended, the chambers cooled off, crystalised, were uplifted, and exposed at the surface. When this happened, the volcanic and sedimentary rocks were deformed, turned up on their end, and eroded. The resulting boulders that were formed roughly 5 to 10 kilometers below the surface under the pressure and weight of the overlying volcanic rocks resulted in the formation of The Baths Pluton. The main eastern portion of the Virgin Island Batholith was formed over a period of 6 million years during the Middle to Late Eocene Period.