Geology

St. Croix began forming millions of years ago from under water volcanic eruptions on the ocean floor. At that time, Central America and the Caribbean Islands that we know today did not exist. Constant motion of the Earth's crust created volcanoes and caused vertical motion of the sea floor. Magma (melted volcanic material) flowed from volcanic vents as ash, lava and pyroclastic flows that cooled to form the oldest igneous rocks in the Virgin Islands. St. Croix's Caledonia formation is an example of those oldest rocks.

The general motion of the Caribbean tectonic plate may have varied locally, widening the Virgin Islands Basin to gradually separate St. Croix from Puerto Rico and the rest of the Virgin Islands. Scientists believe St. Croix may have formed from two separate mountain ranges on the seafloor that were later uplifed and exposed. Thick coral colonies that had grown in the submerged valley between the mountains then solidified to build up the present coastal plain. An abundance of caliche soil in central St. Croix and the ancient reefs dramatically exposed by road cuts provide evidence of this submarine period in St. Croix's geologic history.

St. Croix's northern mountainous area is separated into east and west ranges by these ancient marine sediments that extend in a southwest direction from an area near Christiansted, and include the south-central and southwestern parts of St. Croix. The alluvium transported from these ranges is deposited in wide, frequently merging, alluvial fans that have buried ancient marine sediments at variable depths. More recent, exposed marine terraces are in the south-central, southwestern, and coastal areas, including the Frederiksted area. The mountainous areas are characterized by numerous narrow, steep-sided valleys that have been cut by water flowing down the guts, or intermittent streams, generally in a north to south direction.

Soils

The soils of St. Croix can generally be characterized as shallow (predominately) to very deep; well drained; nearly level to moderately steep soils on alluvial fans, ancient marine terraces and valleys of limestone hills and mountains.

VICTORY - The Representative Soil of The United States Virgin Islands

Victory soils are found on summits and side slopes of volcanic hills and mountains in St. Croix. They are used mainly as rangeland, pasture, and small areas have been subdivided for residential developments.

A typical Victory soil profile consists of a 15 cm topsoil of brown loam and a dark yellowish brown, brown and very pale brown loam to very gravelly loam subsoil to a depth of 84 cm. The underlying parent material is weathered and unweathered igneous bedrock. 

Victory soils are formed in material weathered from extrusive igneous bedrock, mixed origin. These soils have a low to medium fertility and reaction ranges from slightly acid to neutral throughout the profile. These soils are unsuited to cultivated crops.

The word "Victory" was derived from a local Estate, Mount Victory, near Annaly.