The part of Florida that we can see is a platform of sedimentaryÊrocks largely deposited in a warm shallow sea, either close to or far from the nearest hilly land mass. For the last 200 million to 300 million years, this growing rock platform has been moving slowly northward through tropical and subtropical seas. During this time interval, what is now the northern part of the state accumulated riverÊsands, silts, and clays (from the Appalachian Mountains), and the central and southern parts of the state acquired marineÊdeposits containing little of no riverÊsediment.
Rain falling directly on Florida either flows to the sea or soaks into soil and underlying rocks, where it makes up an important water reserve. Runoff in Georgia and Alabama flows into the northern part of Florida in rivers and creeks, where part of it filters downward to become groundwater. Florida does not receive any important supply from the groundwater of other states.
The water that falls as rain in the southeast evaporated from the Gulf of Mexico or the Atlantic Ocean. Because the Florida peninsula is bordered on three sides by ocean, rain is reasonably frequent and abundant over that part of the state. The panhandle obtains plentiful rainfall largely from Gulf of Mexico water. Florida is located close to two large seas: the Atlantic Ocean and the Gulf of Mexico. This position protects the state from true continental extremes of temperature (very hot and very cold). This climate contributes to a tropical to subtropical vegetation pattern in which pine, palm, cypress, and oak predominate.
In the panhandle, drainage is well organized in streams that flow southward from Alabama and Georgia; the Chattahoochee and the Flint rivers combine to form the Apalachicola River, the largest in this southward-flowing set. These are all alluvial; that is, they carry a load of sediment (such as sand, silt and clay) which can be observed as sand banks or as a muddy color. Florida also has nonalluvial rivers. The largest of these is the St. Johns, which flows northward, carrying runoff and groundwater derived from rain that fell directly on the state. The nonalluvial rivers flow across areas having only small relief (that is, having only very low hills) and in general are not eroding their channels; therefore, they carry little or no solid load.
Most of the state's coastline is made up of sandy beaches, saltwater marshes, or saltwater swamps (mangrove swamps). Rocky coasts are present here and there (e.g., on Jupiter Island and near Jensen Beach, on the east coast, and near Bradenton on the west coast). The Florida Keys are made mostly of old, now dead coralÊreefs.
The primary resources of the state are its space, its climate, its water, and its beaches. Secondary resources include petroleum, phosphates, heavy mineral sands, and building materials. Space, climate, water, and beaches are hard to visualize in the resource category, and hard to protect and preserve. In three of these four, at least, there is an ongoing deterioration; maps in this section provide some of the information needed for any wisely designed effort to slow or to halt that deterioration.
This section includes maps based on scientificÊdata and also maps which, although related to scientific work, do not contain observational data (for instance, maps showing the locations of observation stations). Most of the maps have been taken from data files available to the public (e.g., weather bureau records) or from the scientific literature. A few, however, were compiled especially for this volume. Some of the text maps were compiled from too many sources to list separately in the bibliography. In these cases only the five or six key sources are listed.
Considerable effort was made to include wide coverage of scientific information about the state and adjacent waters. However, the presently available data banks are now so vast that it was not possible to make the coverage complete. In some parts of the section, the number of maps could have been multiplied by 10 or 100. From all of this information, only selected maps could be used. These were chosen to provide (a) widely sought information (e.g., rainfall data); (b) information useful for planning; (c) information pertinent to the quality of the environment; and (d) information the reader might find interesting, but did not know that it existed. The reader who wishes more material can turn to the bibliography for guidance.
The section contains true maps (abstractions produced by rational graphic procedures), high altitude photographs, and other imagery (made by combining sequential sensor scans from satellites).
The choice of measure units (British or metric) was difficult because the United States is in transition from the former to the latter. Congress adopted the metric system in 1866. In 1893 the meter and kilogram were established officially as the standard units of length and mass in the United States, and traditional units such as the foot and the pound, were redefined as derivatives of the metric units. In 1988, President Ronald Reagan signed into law a bill which strengthened the favored position of the metric system in the United States, specifically in trade and commerce. Scientists use metric measures almost universally. Recently, many large manufacturing companies have made the switch, to be competitive, and various government agencies are following suit. Nevertheless, many data were collected in the British system and are conveniently given only in that system. The result has been a mixture. Where data were collected in the modern metric system (Systeme International), they have been so presented. For some maps, both kinds of units are shown in an effort to make the atlas easily intelligible, without compromising the data base and without obstructing the trend to worldwide standardization (now essentially complete in almost all countries).
