Pine Island Canal
The Pine Island Canal is a canal, now heavily damaged, which crosses Pine Island in Florida from the Pineland Site on the west side of the island to the [|Indian Field] archaeological site on the east side, a distance of about. The canal was dug about 500 to 1,000 years ago, and is believed to have been used as a canoe route. Much of the canal has been damaged or destroyed by development since the late 19th century. A continuation of the Pine Island Canal may have crossed Cape Coral and been part of a canoe route connecting the Pineland Site with Lake Okeechobee through the Ortona site near the head of the Caloosahatchee River.
Prehistoric canals in the southeastern United States
The Pine Island Canal is one of several prehistoric long-distance canoe canals in southern Florida. The Mud Lake Canal, which crosses the base of Cape Sable in Everglades National Park, is the best preserved of the canals. Nearby is the obscure Snake Bight Canal. The Naples Canal, in Naples, has been destroyed by development. Two canals connect the archaeological site at Ortona with the Caloosahatchee River, bypassing rapids in the river. George Luer suggests that construction of the Pine Island Canal and of similar canals elsewhere in southern Florida are indications of the integration of the region under the Calusa. Shorter canals may have passed through sites with multiple mounds, including Mound Key in Lee County and Big Mound Key in Charlotte County. The mound complexes at the Pineland and Indian Field sites at either end of the Pine Island Canal also had canoe canals passing through them.Other prehistoric canoe canals outside of southern Florida include Walker's Canal, Walton County, in the Florida Panhandle, and the Gulf Shores Canoe Canal in Gulf Shores, Alabama.
Location
Pine Island is low lying, and its shores were largely covered by mangroves. One of the few places providing easy access to the interior of the island from the water was the group of shell mounds at what is now called the Pineland Site. Late nineteenth-century visitors to the Pineland area described a canal extending across Pine Island from the Pineland site. By the 1970s, however, much of the canal had been altered by development, and was in danger of disappearing.The canal crossed Pine Island, connecting the Pineland Site on the northwest side of the island with a couple of burial mounds and a shell key called Indian Field on the northeast side. The canal was long. The Pineland and Indian Field sites date to late-prehistoric and early historic times. The canal was likely dug 500 to 1,000 years ago, and possibly as early as 2,000 years ago. Useppa Island lies opposite Pineland on the west side of Pine Island Sound, and the Cape Coral Canal apparently began on the mainland opposite from Indian Field, so that a straight line from Useppa to more than halfway across Cape Coral stays very close to the Pine Island Canal and the western portion of the Cape Coral Canal. The eastern end of the Cape Coral Canal probably reached the Caloosahatchee River above the open estuary of the lower river. This route would have been shorter than, and avoided the hazards of, the open water of the Pine Island Sound, Matlacha Pass, San Carlos Bay, and the lower Caloosahatchee River.
Condition
Late nineteenth-century visitors Frank Cushing and Andrew Douglas described the Pine Island Canal at its western end at the Pineland Site as being wide and deep measured from the tops of the berms along both sides of the canal. By 1980 the canal through the Pineland Site had become a narrow irrigation ditch As the canoes used by the Indigenous peoples of Florida were on average only wide, and had a draft of no more than, the canal dimensions were ample for canoe use.The western part of the canal beyond the Pineland site crossed land that has been cleared and levelled, and no trace of the canal could be found in 1980. Aerial photographs from the 1970s showed a thin linear feature crossing the eastern part of the island towards the Indian Field site. Ground inspection in 1980 found that the raised ridges flanking the canal were badly eroded, elevated no more than 10 centimeters above the natural ground level, while the canal bed was largely filled in and only a few centimeters below the natural ground level. The canal was overgrown with the pines and saw palmettos that covered the surrounding land. At some points on the eastern side of the island the canal had been further impacted by the cutting of firebreaks and the removal of pine stumps.
Aerial photos from the 1950s, before land on the western side of the island was cleared, clearly showed the canal extending all the way across the island. In those photos the canal bed was consistently about wide, and the raised banks were each about wide, with a total width of.
Construction
A trench across a relatively undisturbed section of the canal in the middle of the island revealed a profile consistent with measurements based on aerial photographs. The swale between the canal banks was about wide, the crest of each bank was about another from the swale, while the crests of the canal banks were about apart. Sand had eroded from the banks into the canal. Differences in the color of the sand in the walls of the trench indicated that the canal bed had originally been about wide below the natural level of the ground, and about wide below the natural level of the ground. A hardpan had formed at the 60 cm level, comparable to the hardpan in undisturbed soil away from the canal. Luer presumes that the canal would have been deeper to reach groundwater. At least of soil were excavated to construct the canal.The eastern end of the canal reaches Matlacha Pass opposite an island called Indian Field. The canal probably continued across the tidal zone of Pine Island, but natural forces and the digging of mosquito control ditches have erased all traces of that part of the canal. Two sand burial mounds were near the eastern end of the canal. One, recorded as "Pine Island 8", was completely dismantled by Clarence Bloomfield Moore in 1900 and 1904. Moore found more than 250 burials in the mound. The second burial mound and another site,, have not been scientifically studied, but vandals removed some human remains from the sites. Artifacts excavated from the Pine Island 8 mound included many of European origin, indicating that the mound was in use after European contact. Luer suggests that the close association of the Pine Island 8 mound, the Indian Field site, and the Pine Island canal indicates that the canal was probably constructed in late pre-Columbian times and continued in use after European contact.
Elevations
The ends of the Pine Island Canal at Pineland and Indian Field were at sea level. The interior of Pine Island reaches elevation above sea level. The canal was no wider at the summit of the island than at its sea level ends, demonstrating that's it was not a sea level canal, as that would have required a much deeper and wider cut in the middle of the island. The canal was not an open channel or sluiceway, as there was no stream or pond to feed water into it. The water level in the canal was probably controlled by dividing it into a series of impoundments separated by control structures. Pine Island has a shallow water table in poorly drained soils, providing a supply of groundwater near the surface. The canal was generally linear, but included bends and curved sections.Pine Island is generally low with flat or gently sloping areas. The island is surrounded by tidal flats covered by mangroves. The interior part of the island is relatively flat, above sea level. A series of terraces running the length of the island successively rise from the tidal flats to the central flat. There are occasional sharp rises between terraces. Drainage is relatively good on slopes, but poor over flat areas, where water from rainfall accumulates, sometimes leaving standing water in slight depressions. The surface sloops more sharply near the eastern shore of the island. Prior to agricultural development in the 20th century, the water table was within of the surface over much of the island during the rainy season, from June to September, but may have fallen to below the surface during dry spells. A shallow hardpan underlay the topsoil across most of the island, slowing the drainage of the topsoil.
The ends of the canal at Pineland and Indian Field are subject to average tides of a little over, which would have had only a minor effect on the water table near the ends of the canal. While the level of fluctuations in sea level that may have occurred over the period the canal was in use probably had little effect on the water table in the interior of the island, even small changes in sea level may have required adjustments to the ends of the canal. The primary factors affecting the usefulness of the canal would have been variations in rainfall.
Water level and flow
Luer and Wheeler used old aerial photographs to trace the route of the canal across Pine Island. They discerned four long curved segments, three long straight segments, and four short segments, as well as segments at the two ends of the canal, for a total of 14 segments. They determined that the straight segments crossed land that was level or very close to level, that the curved segments followed contour lines to avoid depressions in the path of the canal, and that the short segments occurred where there were sharp changes in elevation, generally at the edges of terraces. Some of the long segments diverged from a straight line between the ends, so that the rise in elevation over the length of the segment was minimized.The 14 canal segments proposed by Luer and Wheeler were long. One segment of was completely level, while the other segments had a difference in elevation between ends of. With the difference in elevation across the island, water in the canal would flow downhill, leaving the canal in the center of the island dry, and possibly eroding the banks of the canal. Luer and Wheeler propose that control structures along the canal served as dams to prevent the flow of water during normal conditions, and as spillways to allow excess water to flow to lower levels as needed. The control structures divided the canal into seven or eight impoundments, so that each impoundment would hold the water level high enough to float a canoe at the upper end, but not overflow the canal banks at the low end of the impoundment. Each segment of the canal was deep enough to fall below the normal level of the water table, close to or slightly down into the hardpan, which helped maintain the perched water table. If the water table fell below the bottom of the canal at the upper end of the impoundment, canoes would have had to be dragged over the dry portion.
As the water level in an impoundment would not be parallel to the adjacent water table in July. Digging and maintaining the canal would have been easier during the dry season. Control structures were probably placed at the points on the canal reached by high tides up to above mean sea level, while the tidal segments had to be deep enough to accomate low tides of as much as below mean sea level. No control structures have excavated by archaeologists, but Luer and Wheeler suggest that dams could have been constructed from cabbage palm logs.