The Ridge is a landscape sculpted by the sea and maintained by fire. Over the millennia, rising and receding seas have exposed and covered much of the Florida Peninsula. Following glacial stages, polar ice-caps melted, waters rose, and a series of ridges stood as islands in a vast ocean that covered most of Florida. Isolated from their distant relatives, plants and animals existing on these ridges evolved unique characteristics. The largest of these ridges is called the Lake Wales Ridge. Associated, smaller central Florida ridges include the Lakeland Ridge, Winter Haven Ridge, Bombing Range Ridge, and Lake Henry Ridge. During the last glacial stage -- 20,000 years ago -- the peninsula's land mass was nearly doubled. This connected Florida to the American southwest and narrowed the Gulf of Mexico. Conditions throughout Florida were drier, allowing arid plants and animals to survive. Today, seas have risen to current levels and the central Florida climate is humid and subtropical. A cool dry season gives way to a warm rainy season. Tropical storms and hurricanes form in the Gulf and Atlantic and sweep across the peninsula. The average annual rainfall totals 50 inches. Occasional freezing temperatures prevent the establishment of tropical plants and have moved citrus growers farther south on the Ridge. However, the typical mild winter temperatures, averaging 50 degrees with sunny skies, are inviting to northern tourists and offer a reprieve for local residents. The Ridge is dotted with numerous sinkhole lakes. Naturally acidic rains and groundwater percolate through the Ridge sands into the underlying limestone, gradually creating cavities.
	When these cavities collapse the sands above subside creating valleys and sinkholes that fill with the groundwater in the Ridge sands. Shallower depressions collect rain water seasonally. The Ridge's sandy soils allow rain to drain into the deep Floridian aquifer, a primary source of drinking water. The Southwest Florida Water Management District estimates a 40-foot drop in water levels of the underground Floridian aquifer just west of the Ridge in Polk County since the 1940s. Protection of natural upland communities along the Ridge contributes to the recharge of Florida's deep aquifer.