units, although to a lesser degree upward in the section as paleotopography became 
more subdued. A marine embayment, occupied by the present position of Lake 
Okeechobee and the Florida Everglades, was bounded by topographically higher areas to 
the north and west. These topographic highs, mantled with older Pliocene and Miocene 
elastic sediments, served as sources for detritus throughout Pleistocene deposition. 
During Q1 deposition, quartz sandstones with admixtures of molluscan debris clearly 
reflect the proximity of these topographic highs. More open marine conditions persisted 
in the embayment between the highs where arenaceous, mollusk fragment packstones 
are found interbedded with fossiliferous quartz sandstones. Important faunal elements 
within these embayment sediments include: Chione cancellata, miliolids, peneroplids, 
Manicina, Porites, and Schizoporella. In the northeastern portion of the study area, Q1 
sediments are represented by arenaceous, mollusk-fragment grainstones deposited as 
barrier-beach and beach-dune sediments, and fine-grained quartz sands (lagoonal 
sediments). Lithofacies patterns within the Q2 unit are essentially the same as those 
found in the Q1 unit, except that molluscan packstone increases in the northern part of 
the embayment to the exclusion of quartz sandstone. Generally, the fauna of the Q2 unit 
is similar to that of the Q1 unit. However, more open shelf conditions are suggested by 
scattered occurrences of the coral, Montastrea, along the southern margin of the study 
area. The proportion of carbonates to terrigenous sediments increased markedly during 
deposition of the Q3 unit. Arenaceous, mollusk-fragment packstone deposited in the 
northern portion of the embayment grades southward into foraminiferal, mollusk- 
fragment packstone and grainstone that are relatively free of quartz. Fossiliferous 
quartz sandstones persisted in proximity to the topographic highs. A highly coralline 
facies composed of grainstone and packstone was deposited along the southern margin 
of the study area and marks the first appearance of large numbers of the hermatypic 
corals, Montastrea, Diploria, Porites astreoides, and Porites porites in association 
with encrusting red algae and Halimeda plates. Barrier-beach and lagoonal 
sedimentation persisted in the northeastern portion of the study area where mollusk- 
fragment grainstone, quartz sand, and sandstone were deposited. The upper contact of 
the Q3 unit represents one of the most pronounced of all the Pleistocene discontinuity 
surfaces. Pre-unit topography prior to Q4 deposition was greatly subdued as a result of 
Q3 sedimentation, especially along the southern margin of the study area where coral 
growth resulted in appreciable constructional topography. Maximum relief prior to Q3 
deposition was greater than 120 ft (37 m), as contrasted with approximately 30 ft (9 
m) prior to Q4 deposition. During Q4 deposition, detrital influx was greatly reduced in 
the western part of the study area, but continued to persist in the northeastern part in 
the form of quartz sand and sandstone deposited as a broad, arcuate shoal. To the east 
of this shoal, barrier-beach and lagoonal sedimentation prevailed. Within the 
embayment, mollusk-fragment packstone, wackestone, and quartz sandstone grade 
southward into highly burrowed peneroplid, miliolid, pellet packstone and grainstone, 
which locally contain abundant bryozoans (Schizoporella). This pelletal facies grades 
along the southern edge of the study area into a highly coralline, red algal packstone and 
grainstone facies that is characterized by Montastrea, Diploria, Porites, Halimeda, and 
encrusting red algae. Paleotopography developed on the upper surface of the Q4 unit 
gave rise to a relatively featureless, gently seaward dipping platform on which Q5 
sediments were deposited. In the northeastern part of the study area, arenaceous, 
mollusk fragment grainstone, fossiliferous sandstone, and fine-grained quartz sand 
were deposited as barrier-beach-lagoonal sediments that grade westward into quartz 
sandstones derived from terrigenous sediments shed off the nearby topographic high. 
During Q5 time, the area now occupied by Lake Okeechobee was the site of deposition of 
mollusk-fragment wackestone in what is believed to have been a restricted marine bay 
as suggested by local occurrences of Rangia cuniata and oysters. Southward along the 
present-day Atlantic coastal ridge, the barrier-beach-lagoonal complex gives way to 
an oolitic facies composed of arenaceous, oolith, pellet grainstone and packstone, 
228 
