JUNE 1996

PHASE III DATA RECOVERY ATSITE 22PR533 FOR THE PROPOSEDFLORIDA GAS TRANSMISSION COMPANYPHASE III EXPANSION PROJECT,PEARL RIVER COUNTY, MISSISSIPPI

FINAL REPORT

VOLUME I OF IVCHAPTERS 1 - 6Clifford T. Brown, Connie A. Darby, James A. Green, Jr., Christopher Davies,Michelle L. Williams, Gary Gordon, Frank Vento, and William P. Athens; withcontributions by Justine Woodward, Arlene Fradkin, and Margaret Newman

R. Christopher Goodwin & Associates, Inc.5824 Plauche StreetNew Orleans, LA 70123

PREPARED FOR:

Florida Gas Transmission Company1400 Smith StreetHouston, Texas 77002

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CHAPTER II

GEOARCHEOLOGY AND ENVIRONMENT

Introduction

Whether or not one considers cultural ecology to be a comprehensive theory of human social

behavior, there can be no reasonable doubt that the natural environment played a very large role in

determining the settlement patterns, subsistence strategies, and technological adaptation of the prehistoric

inhabitants of Site 22PR533. Consequently, a review of the environment in the vicinity of the site is

indispensable. The following review of the natural setting of the site areas includes discussions of the

geomorphology, hydrology, climate, flora, and fauna of the project region.

The information presented below represents the results of the geomorphological investigations

conducted at Site 22PR533. The field work, laboratory analyses, and the preparation of the report upon

which this chapter was based were conducted under the supervision of Frank J. Vento, Ph.D., Professor and

Chairperson, Dept. of Geography and Earth Science, and Director, Quaternary Research Institute, Clarion

University of Pennsylvania.

Environmental Background

Geomorphology

Site 22PR533 lies within the East Gulf Coast Plain physiographic region. This physiographic region

consists of cuestas that gently slope southward to the Gulf of Mexico and form a series of arcuate,

southeasterly- to easterly-trending hilly belts that extend across Mississippi. The cuestas are formed by the

differential erosion of gulfward dipping and thickening Mesozoic and Cenozoic sedimentary strata of shallow

marine, deltaic, fluvial origin. The proposed pipeline corridor crosses the southernmost of these hilly belts,

the Pine Hills physiographic province (Figures 5 - 7). The Pine Hills section is bounded to the north by the

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Jackson Prairie and the hilly terrain of the Hatchetigbee anticline and to the south by the Pleistocene

coastwise terraces of the East Gulf Coastal Plain section. The East Gulf Coastal Plain section

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Using the monthly water budget (Thornthwaite 1948; Thornthwaite and Mather 1955) it is apparent

that although the area receives an even distribution of rainfall during every month, soil moisture deficits (albeit

small) occur during four months of the year (May, April, August, and October). Potential evapotranspiration

(PE) exceeds precipitation (P) during every summer month except July. July typically has sufficient

precipitation to recharge the soil moisture slightly even though PE is at its highest total of the year.

Paleoclimate

As depicted by the modern water budget analysis, long runs of anomalously dry conditions are

infrequent. Also, it is obvious from the discussion of the primary seasonal precipitation forcing mechanisms

previously discussed that consistent patterns longer than a few years at a time typically are not maintained

(Vega et al. 1995). This results in few (if any) consistent long-term changes in the modern climate of this

area. However, even though little climate change has occurred during the recent past, large-scale

atmospheric-sea surface interactions may have caused radically different climates to occur over the past few

thousand years.

Evidence suggests (Vento 1995) that negative precipitation (hence surplus) anomalies occurred in

the Pearl River County region between 4200 and 3000 years B.P. Reasons for this 1,200 year climate

anomaly remain speculative. However, it is theorized that shifting SSTs in the Gulf of Mexico after the last

ice age may have been responsible.

Soon after the last continental ice sheet advance reached its maximum extent (18-23,000 B.P), cold

meltwater began streaming into the Gulf of Mexico via the Mississippi River. This effectively lowered SSTs in

the Gulf and contributed to a drier and cooler than normal climate through much of the Gulf Coast states

(Henry et al. 1994). Drier than normal conditions persisted until continental ice sheet ablation opened the St.

Lawrence River. Once opened, the St. Lawrence conveyed much of the cold meltwater to baselevel,

allowing for higher Gulf of Mexico SSTs. This warming brought about substantial climate change in the

northern Gulf Coast. With rising temperatures came increased rainfall. Henry et al. (1994) states that

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conditions in northern Florida approached that of today, warm and wet, by 5000 B.P. Contrary to this

statement are data collected in Pearl River County (Vento 1995). These data, taken along a small first order

stream, show increased sediment accumulation for the period 4200 to 3000 B.P. This suggests that a drier

than normal climate existed, leading to decreased vegetation and more rapid mass wasting and erosion.

From this it is evident that climate conditions in the central Gulf Coast region approximated those of earlier

times in Florida.

The primary reason for such a dry climate in the Central Gulf Coast and a wetter climate to the east,

is localized Gulf of Mexico SSTs. Today, a cold water plume exists in the Gulf of Mexico near the mouth of

the Mississippi River. This plume, evident from satellite measurements of SST, typically exists into mid-

summer. The plume has been documented to disrupt and or change the cyclogenesis and movement of

tropical cyclones through much of the early hurricane season (Vega and Binkley 1991, 1993). It is theorized

that a similar plume persisted in the central Gulf Coast region until approximately 4000 B.P. as a result of ice

sheet and snow ablation in high latitude areas drained by the Mississippi River. East of this plume, SSTs,

would effectively rise, contributing to wetter conditions in northern Florida.

Late Pleistocene and Holocene Paleoenvironments of Western Mississippi

Geoarcheological investigations indicate that the evolution of existing drainage systems and

associated terraces in southern Mississippi are intricately tied to fluctuations in climate, vegetation and sea

level during the Quaternary Period.

The paleoenvironmental investigations conducted during Phase III excavations at Site 22PR533

were largely confined to geological analyses. These alone are not ideal indicators of paleoclimate, however;

they must be considered in conjunction with other regional reconstructions of climate, flora and fauna

(Delacourt and Delacourt 1994; Vento et al. 1994; Kutzbach 1983).

Geologic Evidence

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During the maximum expansion of the Late Wisconsinan glaciation (circa. 18,000 B.P.) there existed

cooler summer temperatures than at present, lowered rates of evapotranspiration, lower sea level (possibly

140 m (459.3 ft) below the present level) and increased soil moisture which combined to increase the volume

of water as surface runoff, producing terrace incision in the southeast.

Runoff and sediment yield are the primary determinants of the physical properties of alluvial

channels and flood plains. The frequency and magnitude of water and sediment yields are adjusted to

climate, vegetative cover, and physiography (Knox 1983:26). Other possible factors affecting flood

plain/terrace development are independent eustatic sea level changes as well as local tectonic and/or broad

epierogenic uplifts.

During the Pleistocene, the aggradational development of most of the major streams in the Pine Hills

section were controlled by climate, vegetational changes, eustatic sea-level adjustments, and variations in

sediment load quantity and composition. A typical scenario that infers valley incision and terrace formation

during the late stages of interglacial and full-glacial periods accompanied by valley aggradation during

interglacial periods may be too simplistic a model when applied to many river systems.

Quaternary geologists who have studied river systems in the Gulf Coastal Plain often presuppose

that those factors which affected the development of specific alluvial episodes along the Mississippi River

also caused similar alluvial episodes along other rivers which drain the Gulf Coastal Plain. Although many

rivers in the Coastal Plain experienced modest incision during the Late Pleistocene in response to lowered

sea levels, none exhibited the degree of incision that occurred along the Mississippi River (Bloom 1983).

Unlike the Mississippi River, the Pearl, Wolf, Pascagoula, and other Gulf Coast rivers did not receive any

glacial meltwater, nor were they affected by the formation of the proglacial Great Lakes, highly variable

climatic and vegetative conditions along their entire lengths, or the effects of post-glacial isostatic uplift.

In general the climate of southwestern Mississippi during the late Pleistocene was dry and cool. The

cause of these dry and cool conditions was the result of depression of the frontal zone below the coast,

development of a positive PNA pattern and the effects of a strong zonal atmospheric circulation. These dry

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climatic conditions would have promoted such plant species as scrub oaks, pine, open-grassy prairies and

savanna areas. Watts and Hansen (1988) have proposed that from 13,000 to 12,000 B.P. climatic

conditions had ameliorated and were warm and moist. Yet even these short warm-moist intervals were far

drier than modern conditions.

Holocene

Saucier (1974) states that a braided stream regimen existed in the Mississippi River Valley until

approximately 9,000 B.P., depending upon location. By that time the Mississippi River was in a meandering

phase as far north as Memphis, Tennessee. Saucier (1974) contends that the oldest exposed post-braided

meander-belt deposits date from approximately 9000 to 7500 B.P.

Muto and Gunn (1979) provide a temporal framework for alluvial episodes along the Tombigbee

River in Mississippi and Alabama by utilizing comparisons with the Mississippi River. Supportive evidence for

their comparative model is based on limited radiocarbon dates in the alluvium overlying the braided stream

deposits and examination of palynological data from the Tombigbee River drainage basin. Based on these

data sets, Muto and Gunn (1979) have developed a tripartite paleoclimatic model for the Tombigbee River.

Their analysis indicates that the Tombigbee River drainage basin experienced three gross episodes of

climatic change during the last 10,000 years. These reconstructed climatic conditions are as follows: 1) The

period between 10,000 and 8000 B.P. is debatable. Results of the pollen analysis indicates a warm/moist

period, whereas the biosilica data indicates a warm and mesic climate. 2) For the period 8000 to 4000 B.P.

both pollen and biosilica data were indicative of a warm/dry period. 3) After 4000 B.P. there is a return to

more mesic conditions. However, extreme caution should be employed in attempting to apply Muto and

Gunn's tripartite paleoclimatic model on a site specific basis. Many of their pollen and biosilica samples were

collected from transported or redeposited alluvial sediments. There is also the fact that their model

fortuitously fits other (i.e., Antev's) such tripartite paleoclimatic divisions for the Holocene which are discussed

in Wright et al. (1983).

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Other investigators have proposed that the early Holocene in southern Mississippi and northern

Florida was a time of warm and dry climatic conditions created by strong zonal atmospheric circulation.

Within the southeast, responses of rivers to Holocene environmental change may be more directly related to

climatic controls (e.g., storms and floods) rather than indirectly to broad-scale climate-induced changes in

forest cover. Knox (1983:32) notes that pollen diagrams from several sites imply that the upland tracts were

essentially treeless prior to 6000 B.P. and that the warm and dry conditions persisted into the middle

Holocene. From 12,000 to 9500 yrs. B.P. southern Mississippi and northern Florida were probably cooler

and drier than at present and water from surface drainage lines was in short supply, especially in inland

locations like Site 22PR533. Access to potable water for consumption would have been primarily from

surface drainage lines (especially during the spring and winter) and from dug holes on the low bottoms of

streams. It is likely that the discharge/flow for surface drainage lines would have been reduced during the

summer and fall throughout the Holocene. These low flows would have been even greater during sustained

warm and dry intervals. The early Holocene environmental changes probably produced appreciable valley

aggradation in response to increases in sediment yields and concentrations (Knox 1983: 33).

Grissinger, Murphy and Little (1981) identified four distinct stratigraphic zones or horizons in

late-Quaternary valley-fill deposits of north-central Mississippi. These four distinct stratigraphic zones

include: 1) organic rich bog-like sediments deposited in a low energy fluvial environment; 2) channel-lag and

bed-load sediments displaying primary sedimentary structures deposited under high energy flow regimes; 3)

massive silts grading upward from slightly bedded silty sand or sandy silt to massive silt and 4) meander-belt

alluvium with some oxbow deposits. Radiocarbon assays of the coarse-grained channel lag deposits

indicate that they were emplaced between 12,000 B. P. and 8,500 B. P., when this portion of north-central

Mississippi probably experienced greater precipitation and surface runoff than it does today. The overlying

massive silts were deposited between 10,000 B. P. and 6,100 B. P., when the climate of north-central

Mississippi was warming and drying and large floods were uncommon. There is good evidence that similar

conditions were also present in southern Mississippi at this time. These warm and dry conditions were

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occurring concurrently with the Hypsithermal (Altithermal) climatic optimum which is so well documented in

the Midwest. Some researchers have suggested that the massive silts are related to ponding in the

tributaries resulting from a rising base-level associated with the aggradation of the lower Mississippi River

between 12,000 and 8500 B.P. (Knox 1983:33). Sand deposits dated at 6100 and 4000 B.P. represent relict

channels incised into the massive silts. The maximum entrenchment into the massive silts, however,

occurred from 3000 B.P. until the time of agricultural settlement, which was associated with lateral channel

migration and meander-belt alluvium composed of overbank, vertical accretion and lateral accretion

deposits. The incision of the massive silts was initiated at about 6000 B.P. in conjunction with the increased

importance of meridial circulation in summer, a condition which favors more frequent large floods (Knox

1983). Knox (1983) contends that base-level was not the dominant factor controlling depositional processes

on many streams in the southeast but rather that, climatic change first, and, second, an associated change in

vegetative cover were more dominant controlling factors affecting stream regimen.

In general, responses of rivers to Holocene climatic variation within the southeastern United States

can be summarized by referring to the well-developed model proposed by Knox (1983). During the early

Holocene, between about 10,000 B. P. and 8,000 B. P., most of the southeast was rapidly becoming warmer

and drier. During this time in response to this post-glacial warming and drying, valley alluviation was

dominant. From the period 8,000 B. P. to 6,000 B. P. most of the southeast was warm and wet with a

decrease in the rate of valley alluviation (Knox 1983: 38). Vegetational changes in response to warmer and

drier conditions may have been an important factor responsible for alluviation in the southeast before 8,000

B. P. Some researchers, however, have indicated that this period of aridity in the southeast may have lasted

well into the middle Holocene. The thick colluvial sediment package separating the Middle Woodland feature

plane from the earlier Archaic deposits at Site 22PR533 may be a result of increased mass-wasting in

response to warm and dry climatic conditions. Based upon bracketing radiocarbon dates and diagnostic

artifacts this dry episode lasted from 4200 to 3000 B.P. It is interesting to note that both the northeast and

midwest also were experiencing drier climatic conditions during this time (Vento, Vega, Rollins, Delacourt and

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Delacourt, King, Toomey and Brush 1995; Knox 1983). The cause of these warm and dry conditions may

have been a westward shift of the Bermuda High, bringing warm-dry air masses into the eastern United

States from Texas/Mexico and more frequent zonal atmospheric circulation. A second later, yet obvious

period of increased mass-wasting at the site occurred in response to historic deforestation.

According to Knox (1983), between 6000 and 4500 B.P. significant valley incision and terrace

development of the early Holocene valley fills was occurring along most drainage lines in the east and

midwest. Knox (1983: 38) offers two causal factors responsible for incision during this time. The first is that

the long-term Late Holocene cooling trend had begun. This cooling improved the forest vegetative cover and

in effect impeded surface runoff and in turn sediment supply to surface drainage lines, thus favoring incision

and terrace development. The second factor is the change from a strong zonal westerly summer circulation

to a summer-dominated meridial atmospheric circulation pattern (Atlantic climatic phase). Meridional

circulation patterns would have allowed for the occurrence of large cyclonic and subsequent high stream

discharges.

As noted above, by 4200 B.P. the warm and dry SubBoreal climatic phase began and lasted until

3000 B.P. This short-lived dry period was replaced by the clearly warmer and moister climatic conditions of

the Sub-Atlantic climatic phase. These warm and wetter conditions promoted incision and relative flood plain

stability from 3000 to 1800 B.P. In the east, many regions were experiencing a renewed episode of vertical

accretion in response to the cooler Scandic Pacific climatic phase beginning at 1800 B.P. This phase was

short-lived and was replaced once again by warm and moist conditions of the Neo-Atlantic climatic phase.

These warm and moist conditions would have favored flood plain stability associated with minor incision. The

Neo-Atlantic phase ends by 700 B.P. when cooler and moister conditions of the Pacific climatic phase occur

and produce renewed active lateral channel migration and rapid vertical accretion on flood plains (Vento and

Rollins 1992). Knox (1983: 39) states that since about 800 B.P. modest alluviation seems to have dominated

most regions until it was ended by late nineteenth century trenching in some regions. Along small drainage

lines, most of this entrenchment was as a result of increased sediment yields and higher surface runoff

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promoted by historic deforestation. It is interesting to note that the two later components present at Site

22PR533 occurred during cool and moist climatic episodes: the Middle Woodland occupation corresponded

roughly to the Scandic Pacific phase and the Mississippian occupation was contemporary with the Pacific

phase.

Paleoflora

Pollen and plant macro-fossil evidence from several sites in the southeast indicate that northern pine

and spruce-dominated forest prevailed in the Central Great Plains, the Ozarks, the Highland Rim and

Cumberland Plateaus, the southern Appalachians, and along the Atlantic Gulf Coastal Plain during the Late

Wisconsinan glacial maximum at approximately 18,000 B.P. (Delcourt 1978; Davis 1983).

By 16,500 B.P. regional climatic amelioration in the southeastern United States was initiated. This

warming trend is clearly reflected in the expansion of cool-temperate deciduous forest species at Anderson

Pond, Boney Springs and Nonconnah Creek. At around 12,500 B.P. the major demise of northern (jack)

pine and spruce forests occurred (Delcourt 1978). These cooler weather species were replaced by Early

Holocene xeric oak-hickory forests. Oak-hickory forests dominated much of the southeast until 5000 B.P.

when they were largely replaced by southern pine forests in the sandy uplands of the Gulf Coastal Plain.

The plant macro-fossil remains from 22PR533 appear to support the conclusion that the modern

flora of the southeast was established by 5000 B.P. Floral specimens recovered from the site were

dominated by pine with very minor secondary elements of hickory and oak. No cold weather spruce or

northern pine floral remains were recovered from the excavations.

The longleaf pine forest system consisted of a mixture of pure longleaf pine forests and two-storied

pine-oak forests. "Intermingled with these general classes were at least seventeen distinct types depending

on site and setting, and with a species diversity involving over forty overstory tree species" (DeLeon 1981:15).

Trees in this system with possible aboriginal subsistence importance include black cherry (Prunus serotina),

oak species (Quercus spp.), honey locust (Gleditsia triacanthos), hickory species (Carya spp.), persimmon

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(Diospyros virginiana), water locust (Gleditsia aquatica), tupelo species (Nyssa spp.), and sassafras

(Sassafras albidum). Understory species with possible subsistence importance include yaupon (Ilex

vomitoria), brambles (Rubus spp.), saw-palmetto (Serenoa repens), prickly pear cactus (Opuntia sp.), and

various grasses.

The longleaf pine (Pinus palustris) forests consisted of a savanna-like ecosystem with an open

overstory of pine. Pine and oak understory were absent in this system, but several species of grasses and

herbaceous plants thrived. These herbaceous species included orchids (Brown [1972:35-42] discusses over

10 species of orchids common in pine forests), pitcher-plants (Sarracenia spp.), sundews (Drosera spp.),

bottle gentian (Gentiana saponaria), rose-gentians (Sabatia spp.), and indigo (Indigofera suffruticosa) (Brown

1972). In the park-like growth of a longleaf pine forest, a person could see almost a quarter of a mile in any

direction and fail to find almost any other type of tree. Where the soils were richer, the overstory contained

trees such as slash pine (Pinus elliotti), short-leaf pine (Pinus echinata), and sweet gum (Liquidambar

styraciflua). Frequent fires kept the understory clear of vines and small shrubs (Braun 1950; Harper 1943;

Lowe 1913).

The more open xeric longleaf pine forests consisted of two-storied pine-oak forests. These forests

were composed of a pine overstory and an understory of scrubby oaks and other pines. The oaks most

commonly present within the understory were the post oak (Quercus stellata) and red oak (Quercus falcata).

Other common understory trees were the bluejack oak (Quercus cinerea), blackjack (Quercus marilandica),

turkey oak (Quercus laevis), and dogwood (Cornus florida) (Braun 1950; Harper 1943; Lowe 1913).

Swamps were common along rivers and major streams, within the shallow upland depressions, and

around the edges of ponds. These swamps contained a wide variety of overstory and understory trees. The

overstory trees included slash pine (Pinus elliotti), black gum (Nyssa biflora), pond cypress (Taxiodium

ascendens), poplar (Liriodendron tulipifera), red maple (Acer rubrum), juniper (Chamaecyparis thyoides),

water oak (Quercus laurifolia), and cypress (Taxiodium distichum). Trees that occurred within the understory

of the swamps were white bay (Magnolia glauca), yaupon (Ilex myrtifolia), tyty (Cliftonia monophylla), and red

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bay (Persea pubescens). The abundance and occurrence of specific trees varied according to the type and

the length of time that the swamp was flooded. Hammocks within the longleaf pine forest were characterized

by trees such as magnolia (Magnolia grandiflora), spruce pine (Pinus glabra), oak (Quercus laurifolia), beech

(Fagus grandifolia), and holly (Ilex opaca) (Harper 1943).

Paleofauna

Pleistocene faunal data was gathered by Muto and Gunn (1979) during Benham and Blair, Inc.,

Phase I archaeological and geoarcheological investigations of the Tombigbee River drainage basin. Muto

and Gunn (1979) conducted a search for Late Pleistocene micro-vertebrates along Catalpa Creek in northern

Mississippi. These investigations were undertaken in the hopes of providing new information on

paleoenvironmental and paleoclimatic conditions existing during the end of the Wisconsinan Stage in

Mississippi. During the course of their field work, 17 new Pleistocene taxa were recovered and added to the

faunal list of Mississippi. Some of the more sensitive paleoenvironmental species recovered include

Synaptomis cooperi (bog lemming) and Microtus pennsylvanicus (meadow vole). Neither of these small

mammals had been noted previously in Mississippi. Currently these rodents occur much father north of

Catalpa Creek and obviously indicate cooler climatic conditions during a portion of the Late Pleistocene in

northern Mississippi. Unfortunately, these species, as well as many other typical warm weather forms, were

found in mixed association. This is due to the fact that the fossil material along Catalpa Creek represents a

fluvially reworked assemblage. Thus, no firm paleoenvironmental or paleoclimatic inferences can be drawn,

other than the fact that Mississippi experienced both colder and warmer episodes during the Late

Pleistocene.

Sand Ridge 1 Site Evolution and Rates of Mass-Wasting

The following discussion is an attempt at utilizing Knox's (1983) model as an aid in illustrating

late-Quaternary fluvial episodes along Murder Creek and its tributaries. It appears likely that the formation of

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Murder Creek began at some point in the Late Pliocene/Early Pleistocene. The Citronelle Formation, which

represents the local bedrock unit, was emplaced during late Pliocene/early Pleistocene time in a shallow

marine-nearshore environment. Murder Creek began its formation shortly after regression of the sea which

emplaced these units. In all likelihood, this newly exposed surface would have developed a series of

rills/gullies (insequent streams) which became enlarged over time through capture of competing drainage

lines. Locally, the uniform spacing of the local drainage lines attests to the consequent evolution of the

drainage system and the later effects of structural controls on these streams.

By mid to late Pleistocene time, Murder Creek had established a larger watershed and began to

more actively downcut in an effort to achieve grade. The southerly dip on the Citronelle Formation exerted

control on the habit and trend of Murder Creek. During the Early and Middle Pleistocene, Murder Creek

probably experienced a number of episodes of valley filling and incision associated with changes in climate,

vegetative cover, and base-level. However, clear evidence of these former valley deposits have been

removed by Late Pleistocene and Holocene erosion and mass-wasting activity.

Throughout its evolution, the small tributary of Murder Creek that runs past the site has exhibited

characteristics of a stream in an initial stage of drainage development, with no well-developed meanders, a

steep gradient, a V-shaped valley profile and a poorly developed flood plain. The moderately well developed

flat bench or terrace which now lies ca. 3 m (9.8 ft) above the active stream channel may represent rapid

lowering of the stream channel in response to Wisconsin low sea level stands. It does not appear that this

higher bench or terrace has received any significant Holocene age vertical accretion deposits (overbank). In

fact, the entire soil profile on this terrace/bench has developed almost entirely from materials mass-wasted

from the adjoining valley slopes and from minor aeolian deposition. The low discharge, emphasis on

downcutting rather than aggradation, and limited competence of Murder Creek at its headwaters would

appear to support this conclusion.

As noted above, the principal sediment transport mechanism at the site is from mass-wasting

(primarily wash and creep). The colluvial sediment/soil package on the toe and footslope is not uniform in

66

thickness. Rather, in those blocks (e.g., N, B, and H) closest to the break in slope, the colluvial soils are

thickest. This occurrence is clearly due to decreased transport competence on the toeslope (Segment 6).

This statement is further supported by the limited number of radiocarbon dates from Middle Woodland and

Archaic features. An analysis of the vertical and horizontal distribution of features which yielded these dates

indicates that two distinct feature planes are present at the site. The upper feature plane is Middle Woodland

in age and in places contains an immediately overlying, more diffuse Mississippian occupation (Beta 81476:

1730+/- 110 B.P.; Beta 81472: 1900+/- 50 B.P.; Beta 81471 1650+/- 60 B.P.; Beta 81474: 2000+/- 50 B.P.).

This upper feature plane occurs in the upper levels of Stratum II (Ab). The second and older feature plane

typically occurs between 30 and 50 cmbs (11.8 and 19.7 inbs) in Stratum III (BwC) and dates to the Late

Archaic and late Middle Archaic (Beta 81473: 3890+/- 50 B.P.; Beta 81475: 5470+/- 120 B.P.). These two

feature planes are separated by between 10 and 30 cm (3.9 and 11.8 inbs) of yellowish brown to brown sand

within the BwC (Stratum III) horizon. While these intervening sands do contain artifacts, no feature plane

occurred in the intervening levels. The implication is that the two feature planes represent moderately stable

surfaces for prehistoric habitation. The intervening sands were most likely emplaced during a dry interval

which allowed for more rapid mass-wasting/colluviation along the valley slopes. This dry episode appears to

correlate with the warm and dry Sub Boreal climatic phase (ca. 4500 to 3000 B.P.). The fact that no

prehistoric buried A horizons occur at the site, except for an exiguous living surface in Block C (Feature 77-

1), indicates that mass-wasting activity has been continuous enough to preclude their development and allow

absorption of the base of the A horizon into the BwC horizon.

Site Stratigraphy

During the course of the Phase III investigations six distinct strata were identified at Site 22PR533. It

should be noted that the pedogenic immaturity of the soils at the site is due to: 1) the high silica content of the

sands which cap the Citronelle Formation which has limited the degree of post-depositional diagenetic

alteration of the silicate mineral suite and 2) frequent episodes of deposition and erosion in the form of mass-

67

wasting with minor aeolian deflation over the last 10,000 years which have in places affected soil

development. These autogenic events have variously stopped, removed, or slowed active factors in soil

formation thus limiting soil development at the site.

In various portions of the site, the thickness of the brown to yellow brown sands increases and the

reddish loam sand deposits of the Citronelle Formation were not encountered during excavation in these

areas. The top of the Citronelle Formation was typically encountered higher in the profile in those areas of

the site which has undergone more extensive deflation and transport of the Pleistocene sands. Locally,

these basal deposits are comprised of the Citronelle Formation which are capped by eolian deposits of late

Pleistocene and Holocene age (Figures 10 and 11).

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Stratum I (A)

Extent: The uppermost stratum, designated Stratum I (A) represents a surface 0/A horizon which

extends from the ground surface to a depth of ca. 12 cm (4.7 in) below ground surface. Stratum I consists of

a very dark grayish brown (10YR3/2). Stratum I is horizontally continuous across the project area.

Texture: Stratum I exhibits a friable, weak fine granular structure, with many fine and medium sized

roots. The stratum is strongly acid and exhibits a sharp, wavy contact with the underlying stratum (Stratum

II). The grain size for Stratum I is consistently unimodal. Unimodal size distributions consistently displayed a

primary mode in the 2 phi size class (.250 mm) with a secondary peak in the 3 phi (.125 mm) size class. The

mean grain size value for Stratum I is 2.25 phi while the mean standard deviation is 2.79 indicating moderate

sorting. The slightly better sorting values for Strata II, III, IV and V reflect the bias of lower organic matter

(roots, rootlets, soil humin) for these lower strata. The mean skewness and kurtosis values for Stratum I are

-0.016 and 0.10, respectively. These numbers indicate an excess of particles in the coarser grain sizes (due

to roots) as well as a mesokurtic (normal distribution) character for the horizon (see Appendix XI).

Color: The color of Stratum I is a dark grayish brown sand (10YR3/2).

pH: Strongly acid

Organics: Many fine and medium roots, with disperse charcoal granules.

Bioturbation: Extensive to Moderate

Cultural Association: Historic, with some redeposited prehistoric lithics and ceramics.

Depositional History: Stratum I was emplaced during historic times in association with accelerated

mass-wasting in response to historic deforestation.

Stratum II (Ab)

Extent: Horizontally Stratum II is continuous across the project area except in the area of prior

pipeline disturbance. Vertically, the top of Stratum II occurs conformably below Stratum I. The stratum is

thickest in Block C and extends to a depth of 60 cm (23.6 in) below ground surface. The average thickness

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of Stratum II is 20 cm (7.9 in). In all cases, Stratum II overlies Stratum III (BwC). The burial of this A horizon

took place during historic times in association with historic deforestation.

Texture: Stratum II exhibits a weak fine granular structure with a moderate number of fine

disseminated roots and rootlets. Stratum II can be texturally classed as a sand and displays a sharp contact

with underlying Stratum III. Stratum II is strongly unimodal with the primary modal class occurring at .250

mm (2 phi) and a secondary mode occurring at 3 phi (.125 mm).

The mean grain size value for Stratum II is 2.56 phi. Stratum II displays a slight fining-upward trend.

The mean standard deviation, skewness and kurtosis values for Stratum II are 2.44, 0.06, and 0.13,

respectively. All samples are mesokurtic to weakly leptokurtic, well-sorted, and display an excess of particles

in the finer grain sizes (4 and <4 phi).

Color: Stratum II ranges from a brown to dark brown sand (10YR4/3).

pH: strongly acid

Organics: moderate, decreasing down profile

Bioturbation: moderate, in the form of small roots and rootlets.

Cultural Associations: The top of this stratum contains the Middle Woodland feature plain

including a living surface, Feature 77-1, in Block C.

Depositional History: Stratum II is a late Holocene A horizon which has been buried by colluvial

sands (Stratum I) emplaced as a result of historic deforestation. The top of the horizon dates from the period

2000 B.P. to historic contact. In sum, Stratum II represents a relatively stable surface during the warm and

moist climatic conditions of the late Holocene. The upper feature plane which occurs at the top of Stratum II

attests to the stability of the toeslope during this time. The warmer and moister conditions of the late

Holocene may also have had a positive affect on the discharge of the small tributary providing higher flows

with clear seasonal surpluses during the late winter and early spring for the aboriginal inhabitants. The

primary limiting factor for prehistoric occupation is a readily available potable water source.

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Stratum III (BwC)

Extent: Horizontally, Stratum III is continuous across the site and is thickest in the western block

excavation units nearest to the distal edge of the toe slope. Stratum III is conformably overlain by Stratum II

and conformably underlain by Stratum IV. The top of Stratum III typically occurred between 33 and 40 cm

(12.99 and 15.75 in) below ground surface.

Texture: Stratum III can best be classified as sand. The primary modal peaks occur at .25 mm (2

phi) and .125 mm (3 phi). The mean grain size for Stratum III is 2.58 phi. The standard deviation value is

2.295 indicating moderate sorting. The skewness value is a positive .068 indicating an excess of particles in

the finer grain sizes. The kurtosis value is 0.14 indicating a mesokurtic character for the horizon.

Color: Stratum III is a yellowish brown sand (10YR5/6).

pH: Strongly acid

Bioturbation: Moderate in upper part, decreasing in lower part of stratum.

Organics: Moderate to minimal

Cultural Associations: Features, lithics, ceramics.

Depositional History: Based upon limited radiocarbon dates and the recovery of diagnostic lithics

and ceramics, Stratum III dates from the period 5000 yrs B.P. to 2000 yrs. B.P. The base of the stratum

marks the end of the warm and moist Atlantic climatic phase and the beginning of the warm and dry

SubBoreal climatic phase. Most of the Stratum III was emplaced during this time in response to more active

mass-wasting processes along the valley slopes. The Archaic feature plane which typically occurs between

35 cm - 60 cm below ground surface in the central and western portions of the site occurs in association with

the base of Stratum III and the end of the Atlantic climatic phase.

Stratum IV/V (C1 and C2)

Extent: Stratum IV and Stratum V (C1 and C2) is based solely on color variation criteria. Both

strata reach their greatest thickness in the central and eastern portions of the site. The top of Stratum IV is

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conformable with overlying Stratum III and conformable with underlying Stratum V. The base of Stratum V,

however, represents a disconformable surface between Stratum VI (Citronelle Fm.) and the overlying

Holocene age colluvial soil package. The combined thickness of these strata varies from 33 to 48 cm (12.99

to 18.9 in).

Texture: Stratum IV and Stratum V exhibit a weak, fine granular structure. Texturally, both strata

can best be characterized as a sand with the primary modal peaks occurring at both .25 mm (2 phi) and .125

mm (3 phi). The mean grain size for both Stratum IV and V is 2.6 and 2.8 phi, respectively (Appendix XI).

The slight fining trend from Stratum V to Stratum IV may be due to both the translocation of finer grain sizes

into Stratum V or as a result of slightly finer grain size emplacement during Stratum V times. This event could

simply be related to less competent mass-wasting in association with eolian deposition.

The standard deviation, skewness and kurtosis values indicate moderate sorting, mesokurtic

character and a tail trending toward the finer grain sizes.

Color: Stratum IV is a brownish yellow sand (10YR6/6) while Stratum V is a yellow sand (10YR7/5).

pH: Strongly acid

Bioturbation: Minimal

Organics: Low, greater in Stratum IV than Stratum V.

Cultural Associations: A few lithics, mostly intrusive from overlying Stratum III, except for a

terminal Paleoindian/Early Archaic point base in Block N that may be in situ.

Depositional History: Strata IV and V are probable early middle Holocene to early Holocene sands

which were emplaced by active mass-wasting processes (e.g., creep and wash) during this time. Based upon

the thickest of these strata, the rates of mass-wasting and deposition on the toeslope appear to be slightly

less than during the period 4500 to 3000 B.P.

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Stratum VI (Citronelle Formation)

Extent: Horizontally, Stratum VI is continuous across the site. Vertically, the top of Stratum VI

occurs higher to the west and is found deeper in the eastern portion of the site. For example, in Block N the

horizon was found at ca. 100 cm (39.37 in) below ground surface while in Block D its top was encountered at

130 cm (51.2 in) below ground surface. Stratum VI represents the basal horizon at the site. The contact

between Stratum VI and Stratum V is wavy, sharp and clearly disconformable.

Texture: Stratum VI exhibits a weak, blocky structure. Organic matter content is extremely low. The

stratum is composed of a yellowish red gravelly clayey sand (5YR5/6). The primary modal peaks occur at

0.250 mm (2 phi) and 0.125 mm (3 phi) with a minor modal peak occurring at 4 mm (-2 phi). There is a

distinct textural and color break between overlying Stratum V (see Appendix XI).

The mean grain size value for Stratum VI is 2.37 phi. The mean standard deviation is 3.97,

indicating poor to moderate sorting. The skewness and kurtosis values are -0.05 and 0.11, respectively.

These values indicate a tail trending toward the coarser grain sizes and mesokurtic character.

Color: Color for Stratum VI is yellowish red (5YR5/6).

pH: Strongly acid

Organics: Minimal

Bioturbation: Minimal. Greater in those units where the formation occurs higher in the section or

closer to the ground surface (e.g., Block N).

Cultural Associations: None

Depositional History: Stratum VI is the Citronelle Formation. Since Stratum VI predates human

occupation of the region, in situ archaeological materials would not be expected. To date, no in situ

prehistoric artifacts have been recovered from Stratum VI.

Summary

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The geoarcheology of Site 22PR533 is revealing. The site lies on the toeslope and footslope of an

upland ridge, in a small, incised, V-shaped alluvial valley. The stream that passes along the eastern edge of

the site has a very low competence and probably never had the capacity to deposit alluvium across the

project area. The watershed feeding the discharge of the stream is very limited in extent, no more than 1

km2 (0.39 mi2). Less than 1 km (0.62 mi) north of the site, the watershed ends at the divide between the Wolf

and Pascagoula drainages. At present, the stream is very small in the summer; the water budget described

above indicates that deficits occur in every summer month except July. These facts imply that stream may

have run dry, at least during the summer months during prehistoric dry climatic phases, making habitation of

the site area quite unlikely.

Paleoclimatic patterns may help to explain the sporadic character of the components at Site

22PR533. The first major occupation of the site, during the Late Archaic period, took place during the end of

the Atlantic climatic phase, a cool period marked by high stream discharges. During the succeeding Sub-

Boreal climatic phase, a warm and dry period, the vegetational cover at the site was reduced and erosion

increased. As a consequence, the Archaic component was interred beneath colluvial deposits created by the

accelerated erosion. At this time, the project area was uninhabited, perhaps due to the desiccation of the

stream. The site remained uninhabited during the succeeding warm Sub-Atlantic climatic phase, except for

an ephemeral occupation represented by a single Alexander ceramic sherd. At approximately 1800 B.P., the

cooler Scandic Pacific climatic phase began and the hiatus in the settlement of the site ended with its

reoccupation during the Middle Woodland period. During the succeeding warm Neo-Atlantic phase, a

second hiatus in the occupation of the project area occurred, but the Middle Woodland living surface was not

deeply buried by colluvium. Only a very small amount of deposition took place within the project area during

this interval. When the Neo-Atlantic phase ended, at about 700 to 800 B.P., the site was re-occupied by

Mississippian peoples for what was probably a relatively short period of time. Finally, the Mississippian and

Middle Woodland occupations were buried under ca. 10 to 20 cm (3.93 to 7.9 in) of colluvium deposited as a

result historic deforestation.

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There appears to be a correlation between climatic phases and the occupational episodes identified

at the site. The site was occupied during three cool and moist intervals, but was consistently abandoned

during the warmer phases. Since it will be shown that the site is a special purpose processing or extraction

locus, the obvious inference is that either 1) the resource being sought in the vicinity of the site disappeared

or retreated during warmer periods, or 2) the stream dried up during those periods, making settlement

inconvenient or impracticable.

Since the occupational levels at the site were buried under colluvium, the sequence of soils at the

site must be composed of a series of buried soils. In the actual soil profile, however, no buried A horizons

are presently visible, with the exception of fragments of a living surface identified just below the modern A

horizon in Block C (Feature 77-1). Thus, it must be assumed that although stable surfaces existed in the

project area during certain climatic phases, they were never sufficiently stable to build an A horizon that was

subsequently interred. Rather, throughout prehistory the A horizon migrated upward with the slowly accreting

surface that was aggrading through colluviation. Consequently, the modern soil profile offered the

excavators no indication of the presence of ancient living surfaces; the only clear indication of the vertical

location of the living surfaces was the placement of the features themselves. While the excavations were

conducted stratigraphically, the interfaces between the natural, genetic soil horizons did not correspond

closely to the ancient occupational surfaces or the depositional episodes within the project area.