Lake Okeechobee Valley and the Everglades. The trough is underlain by clay deposits that compacted more than the limestone and sand deposits did along both coasts of peninsular Florida. Until about 6,000 years ago, the trough was dry land. As the sea level rose, the water table in Florida also rose and rainfall increased. From 6,000 to 4,000 years ago, wetlands formed building up peat deposits. Eventually the water flow into the area created a lake, drowning the wetlands. Along what is now the southern edge of the lake, the wetlands built up the layers of peat rapidly enough (reaching thick) to
South Central Florida Express, Inc. at Marcy and interchanges with the Florida East Coast Railway at Fort Pierce, with haulage rights to CSX and Norfolk Southern at Jacksonville, Florida. The of track on the west side of Lake Okeechobee between Sebring and Lake Harbor was previously a CSX line (Sebring Subdivision along the mainline to the sugar fields, and Okeelanta Subdivision on the spur to Lake Harbor). The northernmost 42 miles of the west side between Sebring and Harrisburg (just south of Palmdale) was built in 1916 by the Atlantic Coast Line Railroad as part of an effort to extend their Haines City Branch south