Bermuda, an archipelago of 138 islands and islets, began as a volcanic seamount that formed in the Atlantic Ocean about 40 million years ago; in fact, it is one of four seamounts that lie in a chain from SW to NE, thought to have developed above a fracture in the North American plate. This volcanic island chain once towered above the sea but, over time, has eroded to the surface by the action of wind, rain and waves. During the Pleistocene, as the sea level rose and fell in concert with the retreat and advance of glaciers, layers of limestone were deposited atop these volcanic pedestals; in turn, this bedrock was covered by sand dunes during warm, interglacial periods.
Today, the exposed landscape of Bermuda is primarily composed of cemented sand and isolated outcrops of limestone; a limestone reef, marking the edge of the seamount, surrounds the archi-pelago. Since the thin soil and porous bedrock does not retain water, the presence of freshwater is extremely limited, primarily available after periods of rain. Nevertheless, a forest of Bermuda juniper, olivewood, palmetto and ferns carpeted these islands before humans arrived; since that time, the harvesting of wood, non-endemic pests and introduced flora and fauna have radically altered this ecosystem. Endemic birds remain, including the Bermuda petrel, but introduced species such as the great kiskadee dominate the avian population.
Though lying in the Temperate Zone, some 640 miles ESE of Cape Hatteras, North Carolina, Bermuda enjoys a mild, sub-tropical climate, thanks to the Gulf Stream which passes just west of these islands. Summer highs are usually in the 80s (F) while mid winter highs range in the 60s; due to the moderating effect of the ocean waters, overnight lows are only 10 degrees cooler. Then again, exposed to hurricanes and ocean squalls, this paradise remains vulnerable to the whims of nature.