# Discovery of an Intact Quaternary Paleosol, Georgia Bight, USA
## 4 Discussion  
The Barge 13 paleosol is a Paleaquult (Ultisol from wet areas with a high groundwater table). Table 2 lists the quantitative parameters evaluated. Base saturation and pH could not be measured, and Cation Exchange Capacity (CEC) is estimated using soil texture and color. We estimate the CEC of paleosol to be greater than 25 meg/100 g based on its high clay and sand content. The argillic horizon, coupled with preserved trees in situ, removed the ambiguity as to the vegetational paleoecology--forested wetland. Multiple preserved, bald cypress stumps and root systems strongly suggest a wetland with hydric soil formation, in this case, an Ultisol with a deep (\(\sim\)0.25 m) Bg clay-rich horizon (Figure 4). The presence of cypress and tupelo pollen and the dominance of pine pollen is consistent with assemblages from surface samples collected on low ridges and flat environments in forested wetlands along the lower Roanoke River [33]. Although pedagenic clays in many wetland paleosols are formed by in situ authigenic processes, the arsenic nature of this paleosol would normally militate against such an origin. However, smectite, whose formation is promoted by seasonal rainfall, is common (\(\geq\)18%) in authigenic clays, and the smectite content of the Barge 13 paleosol is 21%. Pedogenic smectite typically forms authorigenically in poorly drained soils characterized by high pH and CEC [3]. The MIS 3 ages for the Barge 13 are commensurate with those of a 2004 discovery of a drowned cypress forest on the continental shelf off the Alabama coast [35], in which optical stimulated luminescence (OSL) ages for peat and paleosols found there ranged from 72 ka to 56 \(\pm\) 5 ka. Interestingly, at this Gulf site, a paleosol was found only in the base of cores 16 DF8A (\(\sim\)0.1-0.8 m) and 16 DF8B (\(\sim\)0.1-0.6 m) [36]. Soil formation at this site was placed at around 44 ka when this site was subaerial and slightly (1-2 m) topographically higher than surrounding landforms [35]. Aside from the Alabama coast site, the only comparable buried peats and cypress stumps have been of the Holocene age, such as those reported from Murrell's Inlet, South Carolina (9.4-10.1 cal yrBP) [36], and the Georgia portion of Atlantic Intracoastal Waterway (AIAA) (7300 \(\pm\) 40 cal yrBP) [37], which document subaerial exposure during the early Holocene. An even younger exposure was documented from Oregon, where the remnants of a Sitka spruce forest dating to 2000 cal yrBP are preserved on the shoreline [38] (Figure 7). The Reef SAV forest clearly pre-dates the Holocene submergence of the Georgia coastline (Table 1). The preservation of paleosols normally requires their burial and is a result of the specific taphonomic processes found at respective sites. [PERSON] and [PERSON] [39] note that in their study of late Holocene submerged forest soils on the Pacific Northwest coast, \"The  
Figure 7: Preserved prehistoric Sitka spruce forest (Neskowin Ghost Forest) on the Oregon shoreline [39]. The stumps at Neskowin, Oregon, are 2000 years old, according to carbon dating. Used with permission. Arrow indicates stumps exposed by the surf zone. soils deteriorated faster than the stumps. During the first winter season, once stripped of sand, the soil litter (O-horizon) was removed. Removal of the A-horizon followed, but the timing was variable from site to site\". It is likely that the exposure and subsequent submergence of the Barge 13 paleosol and wetland forest followed a similar taphanomic pattern as was observed in Holocene-age records from the Pacific Northwest. All that remains of the Barge 13 soil is the argillic Bg horizon and that of, perhaps, a Bg/C or Bg1 horizon. Wood of both the Pacific Northwest spruce (_Picea_) and southeastern U.S. cypress (_Taxodium_) is capable of surviving submergence. _Taxodium_ is a wetland tree that tolerates long hydroperiods (periods of inundation), and its wood is resistant to water rot and insects, as is the wood of Sitka spruce.