AGE OF THE TRAIL RIDGE LIGNITE PEAT


 The lignitic peat must be somewhat older than Trail Ridge, and if the age of
the ridge were well-established, the peat could be dated. Unfortunately, the age
of Trail Ridge is as debatable as its origin. Alt (1974) has proposed a Miocene
age for the ridge, while Pirkle and Yoho (1970) contend that the sandy body is
no older than Pliocene. Other authors (Cooke, 1939; Hoyt and Hails, 1969)
maintain that the ridge, also known as the Wicomico shoreline, is of Early
Pleistocene age.
 Pirkle and Czel (1983) have identified mollusc fossils taken from a series of
drill holes which penetrated Trail Ridge in southern Georgia. The molluscs all
represent extant, shallow marine species. The lack of extinct species adds weight
to the idea that the fossils and, hence, the ridge can be no older than Late
Pliocene age.
 Rich (1982) stated that the Trail Ridge peat is of Early Pleistocene age,
though his conclusion was based upon the work of Pirkle and Yoho (1970) and
other authors previously cited here. Further palynological investigation of the
TR samples has not gone much further toward establishing the age of the Trail
Ridge peat, though some useful observations can be made which relate Trail
Ridge samples to other deposits from the southeastern United States.
 Elsik (1969) has been able to construct a generalized pollen profile for Gulf
 Coast sediments of Miocene through Pleistocene age. Within the Miocene,
 Quercus is abundant, constituting as much as 20 percent of the pollen assem-
 blage. The Miocene-Pliocene transition is difficult to delineate though Elsik
 states that Ambrosia and Helianthus-type composites are most common in the
 Pliocene, even more common than oak. There is a decrease in Compositae
 (sunflowers, daisies, etc.) and Quercus pollen as Pleistocene deposits are
 encountered, and a general increase in the relative abundance of Pityosporites,
 A/nus, and Taxodium. The fungal spore, Exesisporites also increases in
 abundance in Pleistocene deposits. Darrell (1975) reported on the palynological
 composition of strata from the Georgia coastal plain. There, Miocene and
 Pliocene deposits are characterized by Ouercus-type pollen, while gymnosperm
 pollen generally are either missing or are of minor significance. The exception
 is that Pinus pollen is more abundant in Pliocene deposits than it is in Miocene
 sediments.
 In light of Elsik's and Darrell's conclusions, the following observations can
 be made regarding the Trail Ridge pollen assemblages:

 1. Quercus is of very low abundance in the TR samples. This would suggest a
 post-Miocene age for the peat.
 2. Composite pollen are very low in abundance at all TR sample intervals. TR 1
 samples average 0.50 percent, while TR 2 samples average 0.52 percent. These
 would suggest a Pleistocene age for the peats.