Hamate in Coastal Sands 

of Northwest Florida

By VERNON E. SWANSON. and JAMES G. PALACAS

CONTRIBUTIONS TO GEOCHEMISTRY

GEOLOGICAL SURVEY BULLETIN 1214-B

The distribution and probable origin of 

water-soluble organic material in 

shallow subsurface sands of the 

Florid a.panhandle

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1965
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 20 cents (paper cover)
.CONTENTS

Page

Abstract__ _____________________________________________________ B1

Introduction. _____________________________________________________ 1

Fieldwork and acknowledgments.___-___--__-_-_--_________ ._______ 3

Varieties of humate-cemented sand___--__-_----_____________._______ 5

Processes' leading to humate concentration. ___________________________ 11

Laboratory experiments.--________-__.._---__---___._________.______ 12

Leaching of soil.______-_________-_----_-___-_____-_-_-________ 12

Solubility of humate-______-_____-_-----_----_____-_________-__ 13

 Flocculation-and precipitation of "humate_________________________ 16

Chemical determinations.__________________________________________ 18

. Total.organic carbon in humatercemented sand______._--____-.__ 18

. Ultimate analyses of extracted humate__._-____________-_'---__-__ 18

: Infrared.absorption spectra of humate._____________________________ 21

Spectrographic analyses.___________--_--_-_-____._____________-- 23

. Other analyses._______________________________________________ 24

Summary and conclusions._______________________________________ 25

References. ____ __ ____________________________________________ 27

ILLUSTRATIONS

Page 

.FIGURE 1.: Localities of humate-cemented beach and dune sands near the

-coast of the Gulf of Mexico, panhandle of Florida.________ ,B4

2. Blocks of resistant black humate-cemented sand at the edge

of Choctawhatchee Bay._______________________________ 5

3. Dark-brown to black humate in"beach sand on the south shore

. of Choctawhatchee Bay--_-_-_--_-------------_-------- 6

4. -Blocks of brown humate-cemented sand'eroding from old layer

exposed on. the south -shore of Choctawhatchee Bay _____ 8

5.. The bluff of an .old humate-cemented dune-sand on the south

 shore of Choctawhatchee Bay______________---__________ 9

6. A hole dug in.the.beach sand on the south shore of Choctawhatchee Bay_______________________-__-_---_----_-------- 14

7. Humate flocculating in shallow brackish water near the south

- shore of Choctawhatchee Bay_________ ________________ 15

8. Infrared-spectrum of Florida .humate compared with spectra of

humic. acid of .soil___________________________________ 22

. m
IV CONTENTS

TABLES

Page

TABLE 1. Organic carbon, mineral carbon, and calculated organic-matter 

content of 10 samples of humate-cemented sand from near 

the Gulf of Mexico coast of the Florida panhandle._________ B19

2. Ultimate analyses of humates, in percent, from Choctawhatchee

Bay area________________________________._____________ 20

3. Composition of north Florida humate compared to that of

similar organic substances._______________-_---___-_--___ 21

4. Average composition of north Florida humate compared to

compositions of asphalt and crude oil. _____-----__---_---_ 21

5. Partial chemical analyses of stream water and brackish water 

from Choctawhatchee Bay that are involved in transportation 

and deposition of humate.______________________________ 25
CONTRIBUTIONS TO GEOCHEMISTRY

HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA

-By VEKNON E: SWANSON and JAMES G. PALACAS

.ABSTRACT

Layers of-dune and teach, sand along the north coast of the Gulf of .Mexico 

are cemented or impregnated with a conspicuous dark-brown to.black water-

.soluble organic -substance herein called humate. The humate-cemented sand, 

generally 6 inches to 3-feet thick but as much as 15-feet thick in some places, 

forms one or several irregular layers in .the subsurface of broad-land areas at a 

depth of a few inches to 35 feet. -Ruinate, accumulates in subsurface soil layers, 

in and beneath marsh deposits, in shore and beach sands of bayous and .bays, 

commonly near, the mouths of tea-colored streams and near ground-water seepages,'and as a type of organic sediment in bodies of brackish or saline water. 

The average ash-free composition of the humate is 55.00 percent carbon, 4.4 

percent hydrogen, 38."5 percent oxygen, 1:4 percent nitrogen, and 0.7 percent sul-

. fur, which closely resembles the. composition of lignin, humic .acids, dopplerite, 

and some peat and. lignite deposits.. Infrared -spectra,. amount of benzene-extractable 'hydrocarbons, and - spectrographic .analysis for contained metals

 confirm this similarity.

. This northwest Florida. humate is derived by. leaching from decaying plant 

material, or humus,'on the land surface; surface and subsurface waters transport the soluble and colloidally dispersed humic substances to subsurface sand 

environments. or to brackish or saline water bodies where flocculation or precipitation of humate is triggered by 'various physical-chemical mechanisms. Observations and experiments in the field and in the laboratory demonstrate some 

of the processes of humate-formation, Including floceulation or precipitation by 

adsorption of cations,, complexing with clay .colloids, and. lowering of pH.

INTRODUCTION

A variable, but commonly large, fraction, of. decaying plant and 

. animal material is removed and transported by-natural waters, and is 

subsequently deposited to. form' humate. .The origin, pattern of migration, deposition, and geochemical significance of humate are certainly complex, and are not generally understood by geologists^ though 

. it. is known that soluble organic matter composes a large part of many

Bl
B2 CONTRIBUTIONS TO GEOCHEMISTRY

soils (Waksman, 1936, p. 6); and, at least in a genetic sense, humate 

also may be an important constituent of coal (Hendricks, 1945, p. 11- 

14), black shales, and other carbonaceous sedimentary rocks (White, 

1932, p. 367,370).

A step toward learning more about the origin and chemistry of 

humate has been the investigation of "hasemanite" in the vicinity of 

Choctawhatchee Bay, Fla. This material was first reported and 

named by Haseman (1921, p. 75), though the continued use of the mineral-type name "hasemanite," as proposed in his paper, is unnecessary 

and inappropriate. Haseman (1921) titled his paper "The humic 

acid origin of asphalt," in the belief that the humate in Florida and 

elsewhere was the source material for petroleum. Similarly, Rae, in 

1922 and 1923, pointed to humates as precursors of oil, as did Haseman 

in 1930. More recently, Corbett (1955) ascribed the origin of the 

asphalts of the Athabasca tar sands and the associated "McMurray oil" 

to humic acids and humates, and Gate (1960) suggested that the watersoluble organic materials in soils are transformed into oil (also see 

review by Hedberg, 1964, p. 1762-1763, 1770, and 1776-1777). Humate, however, as it now occurs in the coastal sediments of northern 

Florida, is genetically and chemically in the class of coal, and probably 

only under extremely rare and very local conditions of natural hydrogenation or pyrolysis are humates chemically altered to form fluid, 

gaseous, or solid hydrocarbons.

The terminology and genetic sequence involved in the formation of 

humate are shown below:

PLANTS AND ANIMALS

Death and decomposition 

HUMUS

Leaching

Flocculation or precipitation

HUMATE

As used here, "humus" refers to the accumulation of plant and 

animal residues in an early stage of micr6bial and chemical decomposition found at or .within several inches of the land surface, or that
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B3

complex mass of participate organic matter being similarly decomposed and accumulating at the bottom of a body of water. Humus 

normally is not thought to include skeletal material such as SiO2 

or CaOO3 .

Soluble and colloidally dispersed humic substances are derived from 

humus on leaching by natural water, and are generally observed as 

the tea-colored water of many streams, .lakes, bogs, swamps, bayous, 

and some subsurface water. This water-carried organic material, 

hereafter simply referred to as soluble humic substances, has been 

termed "water humus" by Waksman (1936, p. 304), "soluble humus" 

and "water humus" by Swain (1963, p. 89, 130), and "humic acids" 

by many authors. Further, the fractions of soluble humic substances, 

which are separated by some chemists and: soil scientists, such as fulvic 

acids, crenic and apocrenic acids, hymatomelanic acids, tannins, carbohydrates, proteins and lignins, all of which may be present in the 

Florida organic material, are not used in this.report. As adapted to 

use in geology and geochemistry, the term "soluble humic substances" includes all natural water extracts of peat, soil, and, particularly where undergoing weathering, coal.

"Humate" is here used as a collective term for the group of gel-like 

solid humic substances in sediments, coal-like in composition and 

appearance, that were carried in colloidal suspension or true solution 

by natural waters, and that were flocculated or precipitated from these 

waters on entering a different chemical environment. Humate is dark 

brown to black and is semilustrous. It generally appears as a structureless matrix filling voids and coating grains of a sediment; as such, 

humate may be confused with some hydrocarbons .or asphaltites that 

fill interstices of a rock, but humate lacks the odor, viscosity, and other 

characteristics of oil and has distinctly different chemical composition 

and solubility .characteristics.

In summary, humate is the product of natural flocculation or precipitation of those soluble humic substances in water that were derived 

by natural leaching of decaying plant and animal material, or humus. 

An obvious step in enhancing the genetic and environmental significance of these terms is to be able to refer to terrigenous humus and 

humate and to marine humus and humate. Terrigenous humate in 

the coastal sands of northwestern Florida is the subject of this paper.

FIELDWORK AND ACKNOWLEDGMENTS

The humate occurrences on Choctawhatchee Bay (fig. 1) were 

.first examined by Swanson in 1958, in the company of :and with the 

indispensable cooperation of Dr. L. C. Sharman of Tuscaloosa, Ala., 

who found the first locality that was studied and sampled and who subsequently contributed many valuable suggestions on the genesis of the
B4 CONTRIBUTIONS TO GEOCHEMISTRY

material. Many other outcrops of the humate and several water-well 

sites were studied in 1962 and, with PalacSas, briefly in 1964.

The humate described by Haseman (1921) is the cementing material 

in one or several layers of sand that forms a brown (dry) to black 

(wet) hardpan that is generally a few inches to a few feet thick at 

or near the surface of beach sand. The "type locality" of this humate, 

the place where Haseman presumably quarried and extracted the 

humate for use as a stain for wood, paper pulp, and paints, is on the 

northeastward-trending shore of the northwestern part of Choctawhatchee Bay, Fla., about 1.8 miles east of Shalimar, due east of the 

center of sec. 4, T. 2 S., K. 23 W. (Fort Walton Beach quad, map, U.S. 

Geol. Survey, 1956, 1:62,500). Here the humate-cemented sand is 

clearly associated with ground-water seeps and is strikingly similar in 

appearance to the asphaltic sands of many oil seeps.

Reconnaissance along 150 miles of the coastal area of the Gulf of 

Mexico, from Pensacola to Apalachicola, Fla., resulted in locating and 

studying some 40 exposures of humate-cemented or humate-impregnated beach and dune sands (fig. 1). Subsurface samples of the 

humate-cemented sand were also collected from four water wells being 

drilled near the west end of Choctawhatchee Bay; the cooperation of 

the Echols Drilling Co. of Fort Walton Beach, Fla., in collecting these 

samples is much appreciated and is hereby acknowledged.

.OKALOOSAJ

/ FLORIDA"^

/

N , : ( J _ _. - .

/ x r\ Jl ! Choctawhatchee Bay \'\ " J / L ^.

PensaUa. n/V I ^..R^M^, V _ _ _j \ j 'i

_ __ _ _ _.- T Andrew \ V'

SS.T6-'-"" ^^!.4^ ! / (

GULF OF MEXICO

50 MILES 

I

hicola

FIGURE 1. Localities of humate-cemented beach and dune sands near the coast 

of the Gulf of Mexico, panhandle of Florida. Some dots represent several 

localities studied; four of the dots near the western end of Choctawhatchee 

Bay indicate locations of four water wells from which humate-cemented sand 

samples were collected.
HUMATE IN COASTAL SANDS OP NORTHWEST FLORIDA B5

For those interested, the locations of many key or representative 

 exposures and wells-are described in the body of the report, and the 

name,-publication date, and scale of the appropriate Geological Survey 

topographic quadrangle map are included.

VARIETIES OF HUMATE-CEMENTED SAND

At least seven varieties of humate-impregnated and humate-cemented sand can be arbitrarily differentiated in this area:

1. Black, firmly cemented and relatively resistant, irregularly shaped 

and distributed asphaltlike masses of humate-cemented sand that 

is associated with ground-water seeps; observed at several places 

on the shores of Choctawhatchee Bay and near streams entering 

the Gulf of Mexico. This humate appears to be relatively recent 

in age but may be as old.as.late Pleistocene. (See fig. 2.)

Representative localities: (a) "type locality" of hasemanite

.(Haseman, 1921), locally known as the old dye-plant quarry

(p. B4); (b) about 3 miles northeast of Destir on the south shore

of Choctawhatchee Bay, about 150 yards west of Indian Bayou

(Villa Tasso quad., 1956, 1:62,500). At both localities, long

FIGURE 2. Blocks of resistant black humate-cemented sand at the edge of 

Choctawhatchee Bay; these blocks are eroding from irregularly shaped 

asphaltlike masses associated with ground-water seeps near the edge of the 

bay.

773-597 O-65 2
B6 CONTRIBUTIONS TO GEOCHEMISTRY

sinuous masses of black humate-cemented sand, 2-6 inches in 

diameter and as much as 10 feet long, can be observed that suggest 

humate precipitation around and replacing tree roots.

2. Dark-brown to black, partly cemented or loose impregnated beach 

sand, 1-3 feet thick, located a few to several inches below the surface of the beach, generally in the vicinity of the mouths of small 

streams; observed at many localities on the shore of Choctawhatchee Bay and east of Pensacola on the shores of Pensacola Bay 

and Santa Rosa Sound. This humate appears to be very recent 

and some may be accumulating today; in some places this humate 

may be as old as late Pleistocene. (See fig. 3.)

Eepresentative localities: (a) 2.2 miles east of the OkaloosaWalton County line on the south shore of Choctawhatchee Bay 

where a single-lane road terminates at the beach; NW1/^ sec. 28, T. 

2 S., E 21 W. (Villa Tasso quad., 1956, 1: 62,500); (b) about 2 

miles northeast of Destin on the south shore of Choctawhatchee 

Bay, 0.7 mile southeast of Cobbs Point (Villa Tasso quad., 1956, 

1:62,500).

3. Dark-brown or black, commonly poorly cemented sandy layer of 

irregular thickness, generally only a few inches thick, lying

FIGURE 3. Dark-brown to black humate in beach sand about 3 feet from water's 

edge on south shore of Choctawhatchee Bay and about 10 feet from mouth of 

small stream, ,
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B7

directly beneath or a few inches beneath soil, marsh deposits, and 

other areas of dense vegetation;layer is at .or near the water table; 

roots or root casts common; observed in several roadcuts and 

artificial drainage-channels in Choctawhatchee .Bay area. This 

humate is-in'some places very'similar to the hardpan or ortstein

 . described -and reviewed by Waksman (1936, p. 391-392). The 

 humate is very recent and is currently accumulating.

Representative locality: about 4 miles east-northeast of Santa 

Eosa Post Office (on U.S. Highway 98), on banks of U.S. High-

 way 330 causeway over east part of Choctawhatchee Bay,. about 

.200yards south of;Intracoastal Waterway bridge; center sec..20, 

T. 2 S., R. 19 W. (Point Washington quad., 1947, 1: 62,500). 

4. Generally medium- to dark-brown firmly cemented sand'in a layer

 as much as 3 ,feet thick, commonly .exposed as a ledge or upave- 

_ ment" along.shores of Choctawhatchee.Bay, Apalachicola Bay, 

.. -Pensacola-Bay, and Santa Rosa Sound, and seen/as numerous 

black to dark-brown rounded blocks, as much as 2 feet, across, 

. scattered along the.beach and in the nearshore .shallow water; 

: contains some decomposed roots and root casts and at several localities is associated with, but vertically separated-from old peat 

beds containing, tree stumps. . This variety of humate is of 

questionable late Pleistocene or Recent age. .According to Harper .(1910, p. 294-297), a stratum of peatlike substance, probably 

the humate, was noted as 'long ago as 1827, .and it may A be an 

ancient swamp deposit that extended from Apalachicola Bay west 

to Mobile;-Bay in Alabama and that formed when sea levelwas 

a few feet higher .than at present. (See fig. 4.)

Representative localities: (a) about 40 yards east of locality-(a) 

described under second variety of humate; (b) 2.9 miles east of 

the Okaloosa-Walton County line on .the north shore .of Choctawhatchee. Bay, NE^4/ sec. 28, T. 1 S., R., 21 W. (Villa Tasso 

.quad.,> 1956, 1:62,500); (c) about 20 .airline miles east of 

Pensacola on the north shore of Santa. Rosa Sound, about 100 

. yards due- south of the intersection of U.S. Highway 98 and 

.Florida Highway. 87, SE% sec. 20, T. 2 S., R. .26 W.. (Holley 

.quad., 1936,1:62,500); (d). about 4 airlinemiles west-southwest of 

Panama City,.0.4 mile west of the intersection of Florida Highways 392-and 392A, along.a small stream on the east side of .the 

road that terminates at the north edge of'Grand Lagoon, SE^ 

sec. 9, T. 4 S.,>R. 15 W..:(Panama'City : Beach quad., 1955, 

. 1:24,000); (e) on .shore, of Apalachicola Bay, in Apalachicola, 

1.7 miles east of intersection of U.-S. Highway 9.8 and Apalachicola Airport Road, NWV4 see- *2, T.-9 S., R. 8-W. (Apalachicola 

quad., 1943,1:24,000).

4

,«*
B8 CONTRIBUTIONS TO GEOCHEMISTRY

FIGURE 4. Blocks of brown humate-cemented sand eroding from an old layer 

exposed on the south shore of Choctawhatchee Bay. Note decomposed roots 

and plant fragments on the upper surface of the blocks; these are scarce or 

absent in the lower 6 inches of the blocks.

5. Tan to dark-brown to black, generally crossbedded ancient dune 

sand, which is slightly to firmly cemented with humate; it is 

commonly exposed in 10- to 20-foot bluffs along the shoreline of 

Choctawhatchee Bay, and along some stream channels and in 

25- to 40-foot banks of the Intracoastal Waterway between 

Choctawhatchee and St. Andrew Bay; the distribution and 

amount of humate in the sand apparently were controlled in part 

by variable permeability between and within crossbeds. This 

is an accumulation of old humate, of questionable late Pleistocene 

or Recent age. (See fig. 5.)

Eepresentative localities: (a) exposure in a bank for about 200 

yards on the south shore of Choctawhatchee Bay, same as locality 

(b) described under the first variety of humate; (b) exposure 

that extends about 0.5 mile in the banks of the Intracoastal 

Waterway, Walton County, about 2 miles east of Choctawhatchee 

Bay; it is reached by walking 0.3 mile north-northeast of U.S. 

Highway 98 along a small road 300 yards east of Destin Fire 

Tower; NE*4 sec. 6, T. 3 S., R. 18 W. (Point Washington quad., 

1947,1:62,500). - . . , -
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B9

FIGURE 5. The bluff of an old humate-cemented dune sand on south shore of 

Choctawhatchee Bay. The white sand is colored with humate and ranges 

from light tan to very dark brown; the distribution of the humate is apparently controlled by variable permeability of the dune strata.

6. Very dark brown to black humate-cemented sand is found in the 

subsurface at depths of a few feet to 30 feet, the "hardpan" of 

local water-well drillers; it is generally confined to one layer or 

zone, but two or three layers of the hardpan were penetrated 

locally; these are probably similar to those layers observed in the 

banks of the Intracoastal Waterway (loc. b, in the fifth variety 

of humate). According to local drillers of shallow water wells, 

hardpan was penetrated in about 75 percent of the wells drilled 

in the Choctawhatchee Bay area; and, according to Harper (1910, 

p. 225, 294-295), Sellards and Gunter (1910, fig. 1, p. 96), Martens (1928, p. 46, 73), and Davis (1943, p. 128), a similar hardpan is common at shallow depths in many other areas of Florida. 

The humate in the hardpan may be of very recent age and may 

be accumulating today, though, where more than one hardpan 

layer is present, some layers may be old humate accumulations of 

questionable late Pleistocene or Eecent age.

Eepresentative locality: shallow water well for house, 10 

Guilder St., Fort Walton Beach, at a depth of 17 feet; NE^4 sec. 

14, T. 2 S., K. 24 W. (Fort Walton Beach quad., 1956,1: 62,500).

773-597 O-65 3
BIO CONTRIBUTIONS TO GEOCHEMISTRY

7. Very dark brown to black, generally fine grained humate-containing sediment accumulates in the quieter waters of bays, bayous, 

and lakes; the humate is disseminated in sediment because of 

simultaneous deposition of clay, silt, sand, and particulate organic 

matter; it is observed in series of bottom-sediment cores in bayous 

and in deeper parts of Choctawhatchee Bay and nearby lakes. 

The humate is accumulating today. This occurrence of humate 

is being investigated in a study of the distribution and types of 

organic matter in cored sediments in and near Choctawhatchee 

Bay.

Two or more of the previously described varieties of humate concentration are found at several other localities, for example: (a) about 

8 miles west of Apalachicola and 0.25 mile west of the intersection of 

U.S. Highway 98 and Florida Highway 30; this intersection is reached 

by taking a small road 650 feet south to St. Vincent Sound; exposures 

are in the bank and on the beach of the sound, 750 feet eastward (note 

oyster and Pecten-type shells completely replaced by humate); SE^ 

NW*4 sec. 10, T. 9 S., R. 9 W. (West Pass quad., 1943,1: 24,000).; (b) 

about 1 mile north of Port St. Joe in the south bank of the Gulf Coast 

Canal on the east side of the bridge on U.S. Highway 98 (Port St. Joe 

quad., 1943,1:24,000); (c) about 23 airline miles southeast of Panama 

City and 1.2 miles northwest of the intersection of U.S. Highway 98 

and Florida Highway 386 in Beacon Hill; the exposure is in the south 

bank of a small creek 50 feet southwest of the bridge on U.S. Highway 

98 (note sawed boards projecting from humate-cemented sand; NW^4 

sec. 25, T. 6 S., R. 12 W. (Beacon Hill quad., 1956, 1:24,000); (d) 

about 12 airline miles east of Pensacola on the south shore of Pensacola 

Bay, SW% sec. 24, T. 2 S., R. 28 W. (Pensacola quad., 1941,1: 62,500). 

Several of the varieties of humate, particularly varieties 4-6, are closely 

related genetically and chronologically at a single locality. However, 

the correlation of humate deposits from area to area and the relation of 

the deposits to late Pleistocene and Recent terraces and eustatic changes 

in sea level, particularly to the Pamlico and Silver Bluff shorelines 

(MacNeil, 1950), must be based on future detailed stratigraphic studies 

supplemented by many carbon-14 age determinations.

Once the several varieties of humate and the criteria favorable for 

humate accumulation are known, the finding of humate concentrations 

is relatively simple. The recognition of humate layers is also simplified along this part of the coast of the Gulf of Mexico because the 

dark-brown to black humate-rich layers are in distinct contrast to the
HUMATE IN COASTAL SANDS OF. NORTHWEST FLORIDA Bll

; strikingly white quartz sand that is characteristic of the beaches and 

the dunes.

The humate concentrated in the sand layers is probably far more 

abundant and widespread than determined in this investigation, which 

was based largely on locating outcrops in areas of generally low 

relief. However, as indicated by the localities studied, it is estimated 

that 100,000-1,000,000 tons of humate are present'per square mile at a 

depth of less.than 35 feet, over an area of 300-500 square miles along 

the northern coast of the Gulf of Mexico. Thus, there may be on the 

order of 100 million tons of humate in this area.

PROCESSES LEADING TO HUMATE CONCENTRATION

The.precursors of humate and the likely processes leading to humate 

concentration can be.observed and deduced in the field. In this area 

of humid subtropical climate and of relatively dense vegetation, plant 

matter that falls on the. land surface of the porous sandy soil is rapidly 

.oxidized and decomposed by organisms (Breger, 1951, p. 205; Waksman, 1936, p. 257) to form humus. Rain, which is chemically affected 

by combination with the mist of sea water which is common to coastline areas where the surf is very active (Gorham, 1955 p. 232; 1961, 

p. 805-807; Wilson, 1959), falls on this decaying plant matter, readily 

leaches out the soluble organic material, and rapidly soaks through 

the sandy soil to become ground water. The organic material will be 

transported in solution until a physical-chemical change takes place 

in the water, whereupon this material is.precipitated or flocculated to 

form a humate deposit.

Many variations.in the previously described sequence can be noted. 

For example, much of the water charged with soluble organic material 

accumulates in marshes, ponds, or lakes, and humate may be deposited 

on their bottoms or .in. underlying-sands. Some of the tea-colored 

water is-transported by streams into bayous and bays, and some fraction is eventually carried into the Gulf, of Mexico. Part of the soluble 

organic:matter is probably destroyed by oxidation, bacterial. degradation (Waksman and Carey, 1935), or is biologically consumed (Saunders, 1957), but some is undoubtedly deposited in each environment as 

an integral part of peat.or of the-disseminated organic material in a 

clay, silt, or sand sediment.

Four- basic steps in:the geochemical-sequence of humate formation 

in nature are postulated as follows:

1. Eemoval of the water-soluble fraction from humus by natural 

waters generally rainwater and near-surface ground water; the 

more alkaline the water, the greater the amount of organic matter taken into solution.
B12 CONTRIBUTIONS TO GEOCHEMISTRY

2. Transportation of the soluble humic material in natural surface 

and subsurface waters over distances ranging from a fraction 

of an inch, as into a lower soil or peat horizon, to many miles as 

illustrated by the transportation of tea-colored water from its 

source into rivers, bayous, bays, and ultimately into the oceans.

3. Deposition of humate by precipitation or flocculation from these 

natural waters where they find a different physical-chemical environment, by one or probably a combination of the following 

mechanisms: (a) the adsorption or complexing of dissolved cations such as Al+++, Fe+++, and Mg*+ ; (b) complexing with clay 

colloids; and (c) a lowering of pH.

4. Redissolving, continued transportation, and redeposition of humate 

by repetition of cycle previously indicated.

LABORATORY EXPERIMENTS

In order to verify and understand the several steps in the natural 

sequence of events leading to deposition of the humate observed in the 

field, the probable processes involved were duplicated in the laboratory 

using natural waters and dilute chemical solutions that generally simulate those found in nature. In addition, many samples of humate 

from the Choctawhatchee Bay area were analyzed and characterized 

chemically. The combination of these laboratory data and field 

observations also might help us to understand the distribution of 

carbonaceous material in ancient sediments deposited in coastal environments similar to the present Choctawhatchee Bay area.

LEACHING OF SOIL

In general, the humus content of the soil along this part of the 

Florida coast is very low, even in areas of dense vegetation. The soil 

is sandy, very porous, and apparently well aerated throughout, and the 

humid subtropical climate undoubtedly favors oxidation and accelerated microbial decomposition of the plant matter. The soil consists 

only of a very thin decaying leaf and grass mat, commonly less than 

an inch thick, underlain by a light-brown sand zone a few inches to a 

foot thick which contains roots and some black to brown decaying 

woody plant fragments. Beneath this soil is light-gray to yellowish 

lose sand.

A core sample of soil was taken about 50 feet from the south shore of 

Choctawhatchee Bay in a flat area of fairly dense growth of sawpalmetto and liveoak (for description of vegetation in areas near the 

Florida coast see Kurz, 1942). By means of a separatory funnel having a glass-wool plug at the base, 100 g of this light-brown sandy 

soil, which was 0.7 foot thick, was leached for 6 days with 200 ml of 

distilled water having a pH of 6.0. The water that leached through
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B13

was light yellow -and similar in appearance to some natural water 

collected from streams and lakes-in the area. On addition of a small 

amount of a very dilute FeCl3 solution to the filtered water,-conspicuous flocculation of a small amount of brown humate took place.

The same sample that had been, leached with distilled water was 

similarly'leached with 200 ml of distilled water.containing a small 

amount of NaHC03 , the solution having a pH-of 8.3; a much darker 

more brownish water resulted. This indicated that rain-or .natural 

surface water that might 'be similarly made slightly alkaline in an area 

near marine water would leach even more of the soluble organic 

material from the soil. A brown gelatinous humate also flocculated 

readily from this solution upon addition of dilute FeCl3 .

SOLUBILITY OF HUMATE

One of the unique and more intriguing aspects of the northwest 

,Florida.humate is its demonstrable-mobility. . Humate can be observed 

:in the process of being deposited or of being redissolved at many places 

in the field, and-the process-can be crudely duplicated in the laboratory. It is the.ease and the completeness of removal of the organic 

matter, from the sediment by weakly alkaline to near neutral waters, 

only to be transported and deposited elsewhere, that, suggest specific 

explanations for the ubiquitous distribution of .organic matter as 

carbonaceous films, roll structures, and the like in .some ancient 

sedimentary rocks.

The ^dissolution or remobilizatiorl.of the humate in the Florida sands 

apparently takes place during ordinary physical-chemical changes in 

its hydrologic environment. These changes,-such as an increase in pH 

of surface or subsurface waters or a change from brackish water to 

fresh water, are, in a geologic sense, common and rapid.in this coastal 

area, which is characterized today by .dynamic erosional and depositional processes and hi recent geologic time by the effects of many 

eustatic changes in sea level (Cooke, 1945, p. 12; MacNeil, 1950).

The conditions under which humate eventually becomes immobilized

or insoluble ;in subsurface water have not been investigated, but very

probably dehydration, time, increasing depth of burial, compaction,

and other diagenetic -processes make, the humate "immune, to further

^ attack and redistribution.

To our knowledge,.little study has been .made.of the solubility 

characteristics of humate in sediments under natural conditions. The 

method used in,most.laboratory studies of the water-soluble organic 

fractions in soils and peats is to extract humic acids with an alkaline 

solution such as 0.1 "TV NaOH, 2 percent NaOH, 2^8 percent NH4OH, 

or 10 percent KOH, and, then to'.precipitate the .extract by addition 

of an acid solution such as 0.1 N' H2SO4 or 5 percent HC1 (for ex-
B14 CONTRIBUTIONS TO GEOCHEMISTRY

ample, Waksman, 1936, p. 68; Kononova, 1961, p. 350). Methods 

used in studies of "regenerated humic acids" in coals and black shales 

involve oxidation, commonly with KMnO4 or H2O2 , and then extraction with alkaline solutions and precipitation with acids (for example, Francis, 1954, p. 428; Kinney and Schwartz, 1957, p. 1125). 

Though useful in fractionating and chemically characterizing naturally occurring organic materials, the strong solutions employed are 

extremely rare or absent in nature, and the resulting extracts, from 

the geologists' viewpoint, can only be considered as artifacts.

The solubility of humate can be observed in many ways in the field. 

For example, while collecting samples of humate-cemented sand, one's 

hands generally become dirty and stained a dark brown. Attempts 

to wash off the stain in the brackish water of the bay are fruitless, 

but washing in the water of a nearby fresh-water stream successfully 

removes the stain. Even more significant and interesting is to dig a 

hole into humate-cemented beach sand, which, if near the mouth of 

a fresh-water stream, will rapidly fill with fresh water. The fresh 

water dissolves or disperses some of the humate to become a very dark 

brown, strong coffee-colored fluid (fig. 6). If this coffee-colored

FIGURE 6. A hole dug in the beach sand on the south shore of Choctawhatch.ee 

Bay, which rapidly filled with very dark brown, partly dissolved humate that 

was then swept out into the brackish waiter of the bay and flocculated.
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B15

water is poured into the bay, or if it washes into the bay, the humate 

almost immediately flocculates, or precipitates, and most, if not all, 

of the organic matter in the water is deposited. If the bay water 

along shore is relatively still, the flocculated humate slowly settles 

and is concentrated in the troughs of ripple marks on the bottom sand

Several tests in the laboratory can display to the geologist some of 

the solubility characteristics of humate. Thus, humate placed in 

distilled water does not noticeably color the water ; similarly, humate 

placed in Denver, Colo., tap water, which has a pH of about 5, results 

in only a very slightly straw-colored solution ; and humate placed in 

other waters made very slightly acid to pH 4-6 by addition of HC1 

or H2SO4, a pH which is not uncommon in natural waters, results in 

extremely little or apparently no dissolution.

On the other hand, humate placed in water that is slightly alkaline 

rapidly dissolves, and the water becomes a dark brown, the color of 

very strong clear coffee. These slightly alkaline solutions can be made 

with reagents such as NaHCO3 , Na2CO3 , NaOH, or NH4OH, one or 

more of which may be present in natural slightly alkaline waters at

FIGURE 7. Humate flocculating in shallow brackish water near the south shore 

of Choctawhatchee Bay. Note how the humate (dark) is concentrated in 

troughs of ripple marks. Crests of ripple marks are 3-5 inches apart, water is 

about 1 foot deep. Humate-laden water is from the hole shown in figure 6.
B16 CONTRIBUTIONS TO GEOCHEMISTRY

pH 7.5-9. Of course, the more alkaline the laboratory solution, the 

more rapid the dissolution of the humate; thus, a fragment of black 

humate-cemented sand .rapidly disintegrates to loose white sand in, 

for example, a 0.1 N NaOH solution. The same result, however, has 

been obtained in several laboratory experiments using water made 

only very slightly alkaline to pH 8.3 by addition of NaHCO3 , and to 

pH 8.5 by addition of Na2CO3 . The only difference between using a 

weakly alkaline solution and using a strongly alkaline solution is that 

more of the weakly alkaline water must be passed through the same 

material during a longer period of time in order to dissolve the humate 

completely.

It should also3 be noted ; that -the organic matter in many of the humate-impregnated sands is largely, if not entirely, humate; particulate 

fragments of organic matter such as wood or root fragments are rare. 

The dark brown to black sand leached with- slightly alkaline water is 

 left completely white except, for a few scattered detrital grains of magnetite and ilmenite,. and analyses -indicate that 95 percent or more of 

the organic matter is removed by leaching.

FLOCCTTLATION AND PRECIPITATION .OF HUMATE

Preliminary laboratory tests show .that humate can be readily flocculated, or precipitated from1 slightly alkaline water containing redissolved humate and.from natural tea-colored fresh water by .the addition of dilute solutions of FeCl2 , FeO3 , MgCl2 , Aids, A12 (SO4 ) 3 , 

OaCl2 , CaSOi, BaCl2 , and .EC1 solutions. Iron,'magnesium, aluminum, calcium, barium, and potassium are elements present in solution 

in :sea water ('Sverdrup,. Johnson, and Fleming, 1942, p. 176), and, 

as shown by some 15 spectrochemical analyses of. humate and humatecontaining sediment, one or several of these.elements is-present in 

sufficient amount to indicate ions responsible for humate flocculations. 

Aluminum, iron, and magnesium very likely are the elements that are 

primarily responsible for the flocculation of most of. the humates in 

this-coastal area*of Florida,, either in bodies of saline or brackish water 

or in the subsurface sands on land.

Samples of filtered Oyster -Lake water and Gulf of Mexico water 

were mixed in the laboratory in proportions of 1:1,1: 2,1: 5, and 1:10. 

Oyster Lake is a few hundred feet from the 'Gulf of Mexico.and about 

10 miles.east of the Walton-Okaloosa County line, SW-^4 s®0- 3, T. 3. 'S., 

R. 20 W. (Point.. Washington quad., 1947, 1:62,500). .The .small 

stream that discharges Oyster -Lake water into the- Gulf of Mexico en- 

.ters the pounding surf of the gulf and the dark water is so rapidly disseminated that no flocculation could be observed in the field. At the 

time of mixing of the waters in the laboratory, no flocculation was
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B17

observed, nor was there any apparent flocculation after the covered 

tubes were allowed to set for 10 days, so the experiment was set aside 

with the premature conclusion that no flocculation would occur. However, at some time between 10 days and 65 days after mixing, very 

obvious flocculation had occurred, and the amount of flocculate at the 

bottom of each of the glass tubes apparently was proportionate to the 

amount of Oyster Lake water in the mixture. No flocculation or 

precipitation was observed in reference tubes of "pure" Oyster Lake 

water or Gulf of Mexico water, which suggests that microbial action 

was not the cause of flocculation. Once again the factor of time was 

shown to be of great importance in understanding natural phenomena, 

particularly in geologic studies, but it is this factor of time which is 

so commonly ignored or underestimated in laboratory experiments 

designed to duplicate these natural phenomena.

Laboratory tests also have been made to observe the flocculation or 

precipitation of Florida humate from slightly alkaline water containing redissolved humate and from tea-colored stream waters by addition 

of acidic solutions. The pH of the waters was carefully lowered by 

the addition of dilute HQ or H2'SO4 , for example from pH 8.3 to 4.5 

(the general range of pH of natural waters in sedimentary environments is pH 9-3; see Baas Becking and others, 1960, fig. 31). At a 

pH of about 5.5, slight flocculation can be observed, and at a pH of 

about 4.5, massive flocculation takes place, which is almost a "flash" 

reaction.

As indicated by the beautifully preserved "fossil" shells in the black 

humate-cemented sand on the beach of St. Vincent Sound (loc. a, p. 

BIO), acid waters completely dissolved the calcareous oyster and Pecten-type> shells and humate was subsequently deposited in the resulting 

voids. However, shells buried in brown humate-cemented sand at a 

few other localities have not been appreciably altered, which suggests 

that the humate-depositing waters were not acidic enough to dissolve 

CaCO3 .

The amount of humate deposited in this coastal environment as a 

result of lowering of pH is not known. A few random determinations 

of the pH of water in sediments where humate has been deposited or 

is accumulating indicate an acid environment of pH 4-6. The fact, 

though, that some pH measurements of coffee-colored stream and lake 

waters are also slightly acid is puzzling, and the natural flocculation 

or precipitation of humate solely by pH changes is still not clear. Possibly the pH of waters below the surface of marsh areas and in the 

intermittently stagnant bottom waters of some lakes and bayous is in 

the 3-4.5 range and may account for humate deposition.
B18 CONTRIBUTIONS TO GEOCHEMISTRY 

CHEMICAL DETERMINATIONS

To those familiar with carbonaceous rocks, the humate-cemented 

sand in Florida would appear to contain 15-25 percent'organic, matter. 

This estimated content might be expected because the:sand is black 

where wet, and, in places, resembles solid blocks of asphalt. However, 

.on close observation with a hand lens or under a microscope, the black 

sand is seen to be really a quartz sand whose grains are stained or 

coated with dark-brown organic matter humate that composes only 

a small percentage of the total sediment.

TOTAL ORGANIC CARBON IN HUMATE-CEMENTED SAND

The organic carbon content of the humate-cemented sand, as determined from analyses of 10 samples of several varieties, ranges.from 

0.57 to 5.42 percent (table 1). The organic carbon content can be 

crudely, estimated on the basis of color, the blackest sand containing 

the most organic carbon. As also shown in table 1, mineral, or carbonate, carbon is negligible in these coastal sands, generally less than 

0.05 percent. This indicates, that carbonate minerals such as calcite 

are scarce or absent.

The: total organic matter of the humate-cemented sands has been 

calculated to range from slightly less.than 1 to above 8 percent (table 

1). This is based on ultimate analyses of .the humate, which are discussed in the following section, and on the organic carbon determinations. In-comparison with some organic-rich rocks, this range is 

-seemingly low, but it should be recalled that this organic matter consists almost completely of water-soluble organic material, or humate. 

Peat deposits and the black organic-rich bottom sediments from the 

.marshes, lakes, and bays in this part of Florida, which contain, abundant particulate plant matter, and variable amounts of humate, contain 

much more total organic matter but are excluded from consideration in 

this paper.

ULTIMATE ANALYSES OF EXTRACTED HUMATE

The average composition of the humate currently being deposited in 

and near Choctawhatchee Bay; on a moisture- and ash-free basis, is 

55.0 percent carbon, 4.4 percent hydrogen, 38.5 percent oxygen, 1.4 

percent nitrogen, and 0.7 percent sulfur. This average is based on 

three ultimate -(elemental) analyses .{table 2) of two varieties of 

humate; samples S62-5B1 and S62-5B2, which are chemically sepa- 

. rated humates and whose analyses were; averaged, represent one variety 

currently ^accumulating in beach sand on the south shore of Choctawhatchee Bay, and sample S62-38A represents humate deposited from 

stream water.
TABLE 1. Organic carbon, mineral carton, and calculated organic-matter content of 1

the Gulf of Mexico coast of the Florida panh

[Humate composes an estimated 95-99 percent of organic matter. Classification of varieties of humate given in 

analyses by I. C. Frost; total organic matter calculated from organic carbon content using conversion factor o

(table 2)]

Variety and locality 

(keyed to 

descriptions in text)

la..... ..............

2a

2a

2a . 

4a.. ...... ... ..

«»4b . . -. .

4c . 

5a -'-.. . ........

5a ~ _ .. . .-

6a... .............

Field No.

S64-22C

S62-7

S62-5

S62-1

S60-1

S62-3

862-16

862-10

862-11

S62-8

Laboratory No.

D116576

D 112612

D112611

D112609

D 112608

D112610

D112616

D112614

D112615

D112613

Description

below water level of western shore of Choctawhatchee Bay (old 

on south shore of Choctawhatchee Bay.

south shore of Choctawhatchee Bay.

shore of Choctawhatchee Bay.

water level of south shore of Choctawhatchee Bay.

bank, a few feet above and back from north shore of Choctawha

about 1 ft above water level of Santa Rosa Sound.

1-6 ft above beach on south shore of Choctawhatchee Bay.

Bay, eroded from bluff of dune sand (S62-10).

17 ft in water well in Fort Walton Beach.
B20 CONTRIBUTIONS TO GEOCHEMISTRY

TABLE 2. Ultimate analyses of humates, in percent, from Choctawhatchee Bay

area

[A, moisturerfree analysis as reported; B, calculated analysis, ash free. Analyses of S62 samples are ultimate 

analyses by .Huffman Laboratories, Wheatridge, Colo.; extraction of S60-1A by I. A. Breger; ultimate 

analysis by Coal Laboratory, U.S. Bur. of Mines, Pittsburgh, Pa. Other analyses of S62-5 and 860-1 

in table 1J

Carbon ............

Ash.... .... ... .....

Total.... .

, S62-38

Humateclay sediment,

flocculated

from stream

water by bay

water

A

20.19

2.24

17.20

.42

.21

62.38

102.64

B

50.15

5.57

42.72

1.04

.52

100.00

S62-38A

Humate

extracted from

S62-38 by.

NH40H,

flocculated

with H2S04

A

39.53

2.96

26.89

1.36

.40

27.26

98.40

B

55.57

4.16

37.80

1.91

.56

100.00

S62-5B1

Humate

extracted from

S62-5 with

NaOH,

flocculated

with HjSOi

A

31.69

2.58

25.07

.53

.50

43.74

104.11

B

52.49

4.27

41:53

.88

.83

100.00

S62-5B2

Humate

extracted from

862-5 with

NaOH,

flocculated

with HC1

A

36.60

3.11

23.85

.62

.65

38.28

103. 11

B

56.46

4.80

36.79

.95

: oo

100. 00

S60-1A

Humate

extracted from

S60-1 with

NaOH,

flocculated

byHCl

A

32.6

3.5

37.5

.7

.3

25.4

100.0

B

43.7

4.7

. 50.3

.9

.4

100.0

The elemental composition of all the humate samples is very similar, 

as indicated by the analyses in table 2. When the analyses are compared on an ash-free basis, the few notable but minor differences in 

composition are readily, explained by known characteristics of the individual samples. Sample S62-L38, which has a slightly higher hydrogen and oxygen content and slightly lower carbon .content, is a sample 

of the whole sediment-flocculated, from stream water; some nonhumate 

particulate organic matter of clay size undoubtedly was included in this 

 sample. 'Sample S62-38A, which has a slightly higher nitrogen content, is humate extracted from the humate-rick sediment of sample 

S62-:38 by dilute NH4OH solution; about 1 percent of a nitrogen salt 

undoubtedly was included with the .humate recovered. Sample S60- 

1 A,, which relative to other samples has a lower carbon content and an 

almost exactly correspondingly higher oxygen content, is. a sample of 

an old moderate brown humate-cemented isand. layer .which has been 

deeply weathered.

The chemical composition of the Florida humate puts it into the 

general class of coaly or humic material (Twenhofel, 1950, p. 463). 

As a recently deposited organic substance, humate is very similar in 

composition to humic acids derived from soils and to the soluble organic 

matter in streams and lakes (table 3), and the humate is compositionally not very different from lignin, a plant constituent believed by 

Davis (1946, p. 62),.Breger (1951), and by Flaig (1964, p. 1523) to 

be, at least in part, a.precursor of humate, as used in this paper. The 

Florida humate is certainly very similar, in appearance and genesis 

as well as composition, to both dopplerite in peat and a doppleritelike 

material naturally extracted by alkaline water from a Cretaceous coal
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B21

bed (table 3). The composition of humate is also generally similar 

to that of some peat (Davis, 1946, table 12) and lignite samples.

In general appearance, humate-cemented sand resembles asphaltimpregnated sand, but the elemental compositions of humate and petroleum substances are distinctly different (table 4). Asphalt and 

crude oil, which are composed predominantly of hydrocarbons, contain little or no oxygen, whereas the oxygen content of humate and 

humic materials is 30-50 percent (also see table 3); the carbon and 

hydrogen contents of the two classes of carbonaceous materials also 

are clearly dissimilar.

TABLE 3. Composition of north Florida humate

[A, compared with that of B, the average of humic acids from seven main soil types of U.8.S.B. (Kononova, 

1961, p. 90); C, "water humus," or soluble organic matter transported by streams (Waksman, 1936, p. 291); 

D, "humolimnic acids " an ethyl acetate extract of yellow coloring matter in lake water (Shapiro, 1957, 

p. 167); E, fossillignin (Francis, 1954', p. 351); F, dopplerite (analysis by Doppler, in Waksman, 1936, p. 281, 

recalculated to ash-free basis; also see Clarke, 1924, p. 763); Q, doppleritelike material derived and transported from Cretaceous coal in Wyoming (Vine, 1959). All analyses in percent on ash-free basis]

O YVtmn

A

Florida 

humate

55.0

4.4

38.5

1.4

.7

B

Humic 

acid

60.34

4.16

31.66

4.26

C 

Water humus

45-54. ........

3.86-5.05... 

38.8-47.9.... _ ..

1.46-4.23 

D

Humolimnic 

acids

54.56

5.64

39.12

1.23

£

Fossil 

lignin

56.7

5.2

36.2

1.9

F

Dopplerite

61.1

5.3

42.5

1.1

Q

Doppleritelike material, 

Wyoming

62.2

3.6

29.3

2.2

2.7

TABLE 4. Average composition of north Florida humate compared to compositions of asphalt and of crude oil, in, percent

[Cited from Levorsen, 1954, p. 322]

Carbon -_-_---___-_________________-

Hydrogen

Oxygen _____________________________

Nitrogen. _ __________________________

Sulfur... __________________

Florida 

humate

55.0

4.4

38.5

1.4

.7

Asphalt

80 -85

8.5-11

.1-4.5

0-2

2-8

Crude oil

82. 2-87. 1

11. 7-14. 7

. 1-1. 5

. 1-5. 5

INFRARED ABSORPTION SPECTRA OF HUMATE

As another step in understanding and characterizing these humic 

substances, infrared absorption spectra were obtained on several samples. The humate was generally extracted from the impregnated 

sands with NaOH, flocculated with HC1, and evaporated to dryness. 

The infrared spectra were then obtained on the humate as pressed 

KBr pellets (J. H. Turner, analyst).

All the spectra showed similar absorption characteristics, with 

marked peaks at about 3.0/t, 5.9/*, 6.2ft, and 7.2/_. Broad bands and
B22 CONTRIBUTIONS TO GEOCHEMISTRY

minor peaks were also observed in the regions of 8.1/*, 9.2/u,, 9.7/* and

. llju,. The spectrum of humate. extracted from sample S62-5 (.tables

1 and 2) is shown in .figure 8. Spectra of three similar substances are

FREQUENCY; IN .CENTIMETERS4000 3000

100

2000 1600 1400 .1200 1000 800

80/1

60

40

20

100

 80 -

Z 60 -

O

cc

Q_

Z 20 -

LUo 100

f- 80h

CO 60 -

QL 40 I20

100

80

60

40

20

0

3

I I

A Florida humate

,8 Soil-humic-acid, 

Florida

C Soil humic acid, 

 North Carolina

D Doppleritelike 

material, Wyoming

6 7 8 9 10 11

WAVELENGTH, IN-.MICRONS

12 .13 14 15

.FIGURE- 8. Infrared- spectrum of A, 'Florida humate compared with spectra

, of B, humic acid of soil from same area in. Florida; C, humic acid of soil .from

North Carolina (R. .L. Malcolm, 1964, unpub. Ph.D. thesis, North .Carolina

-State.Univ.) ; and D, a sample of .doppleritelikelmaterial from same locality

in Wyoming reported by Vine (1959).
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B23

included in figure 8 for purposes of comparison. Two of these spectra 

are of humic acids extracted from soils, and one is a spectrum of doppleritelike material.

The most characteristic peaks of the humate spectra are the absorption maxima at 3.0/*, 5.9/x, and 6.2/*, which are normally attributed to 

hydroxyl (OH), carbonyl (C=0), and carbon-to-carbon (C=C) 

double-bond stretching vibrations, respectively. The inflections in 

the absorption region between 7/* and lip, are generally broad and 

indistinct; structural interpretation at this time would be unwarranted without further chemical treatment of the samples. Comparisons of the infrared spectra, however, indicate that the chemical 

structure of Florida humates closely resembles the structure of humic 

acids, especially those derived from soils.

SPECTROGRAPHIC ANALYSES

Analyses by the six-step spectrographic method (concentrations of 

elements reported in six steps per order of magnitude, for example, 

0.1,0.15, 0.2, 0.3,0.5,0.7, and 1.0) of nine samples of humate-cemented 

sand show little variation in the number of elements detected and 

amount of each element. The nine samples represent all of the seven 

described types of humate occurrences, except bottom sediment from, 

for example, a bay. The following is the approximate average composition of the humate-cemented sand, given in percent, based on the 

nine spectrographic analyses (J. C. Hamilton, analyst):

0.0003

.001

.001

.0005

.0003

.007

Some 34 additional elements were also looked for spectrographically 

but were not detected.

Analyses by the six-step spectrographic method of three samples 

of humate, all from the south shore of Choctawhatchee Bay, are also 

consistent in the number of elements detected and the amount of each. 

The humate in these samples was extracted and air dried as described 

for infrared analysis and analyzed on an as-received basis. The humate, on the basis of the spectrographic analyses, which excludes such 

elements as the halogens and those common to organic compounds such 

as carbon, hydrogen, oxygen, nitrogen, and sulfur, has the following 

approximate average composition, given in percent (J. C. Hamilton 

and Barbara Tobin, analysts):

Si _________

Al ______

Fe ___ __

Mg _ ._

Ca _ __ _

Ti _________

. _____ >10.0

. _____ .7

._ ___ .07

. _ __ . 02

._ ____ .02

. _____ .05

Mn ___ _____ _

B __ _____________

Ba __________________

Or ________ __

Cu ______ _______

Zr _____ _ ___
B24 CONTRIBUTIONS TO -.GEOCHEMISTRY

Si _ _ .

Al ___ .

Fe

Mg __ __.

Ca . __.

Na ___ .

Ti _ __ .

Mn ___ .

Ba __, __.

. _ 3

.- .7

.__ .3

. _ .07

... ,02

._ . 1. 5

. _ .3

. _ ..0007

. __ .007

Be _

Ce

Co _ _

Or _ __

Cu

Ga _ _

La _ _

Nb

Nd __

-__ _ 0.0005

_____ .02 .

_ __ .0005

___ .01

.002

___ _ .002

_ _ :01

. 0015

.007

Ni __ _

Pb

Sc

. Sr _____

 v

Y

Tb .__

Zr _ _

_ _ ,0.0015

_ _ .003

__ _ .003

001

__ _ .005

_ __ .007

__ __ .0005

__ _ .005

These spectrographic analyses suggest that the humates on this 

part, of the: Florida coast are predominantly organic aluminum complexes that have concentrated large .parts .of the available iron, titanium, cobalt, chromium, copper,. lanthanum, nickel, lead, scandium, 

vanadium, and possibly other metals-in :these coastal sediments. The 

number and concentrations of-metals, however,.in either the humatecemented sand or the humate do Jiot differ from or exceed those commonly found in organic-rich sediments.

Preliminary investigations indicate that the amount of hydrocarbonlike substances in the humate-rich sediment is relatively very 

small. A benzene Sohxlet extraction :of one of the humateTimpregnated beach sands, sample S62-5 (also see tables 1 and 2), yielded 

200 parts per million (ppm) of extract, which is 0.02 percent of the 

dried sediment. .The extract was yellow and waxy in appearance and 

fluoresced slightly under ultraviolet light. If .the-total organic matter 

of the humate-rich sediment-is considered to be 2.26 percent (table 1), 

the hydrocarbonlike extract would compose about 0.9 percent of the 

organic matter. The -remainder of the organic matter is presumed 

to be humate and is not soluble in benzene.

An X-ray analysis was made by L. G. Schultz (written, commun,, 

.1964) on, the sediment derived from tea-colored stream water by natural, flocculation in the brackish water of Choctawhatch.ee' Bay. This 

naturalflocculate (S62-38) is about 40 percent humate (table 2) .and, 

according to Schultz, about 60 percent clay; the clay is composed of 

a poorly crystallized kaolin mineral which perhaps is -halloysite and 

of dioctahedral vermiculite, in about equal amounts.

'The-role that natural water plays in the geochemical processes of 

humus-leaching and the transportation and deposition of humate is 

extremely important, though little is known about this water, at present. The chemical composition of rainwater and dew near the coast 

and the distribution of these chemically affected waters* are probably 

 of special significance in the initial leaching of humus, as is suggested 

by studies by Wilson (1959) and Blanchard (1964). Certainly the 

haze produced by the Gulf of Mexico surf is strikingly visible on a
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B25

clear day; it rises several hundred feet in the air and extends as much 

as half a mile inland. The salt in this haze actually is a driving 

hazard as it accumulates on the windshield of a moving vehicle.

Two samples of water were collected near the mouth of a small 

stream entering the south side of Choctawhatchee Bay, 2.2 miles east 

of the Okaloosa-Walton County line (loc. a, second variety of humate), near where samples S62-1, S62-5, S60-1 (tables 1 and 2) were 

collected and where abundant humate is now present. Partial chemical analyses of the stream water and of the brackish water of the 

bay are given in table 5. The difference in amounts of dissolved ions 

between the stream water and the bay water is striking; the bay water 

contains about a hundred times more than the stream water. For 

comparison, the brackish water of this part of Choctawhatchee Bay 

has about one-third the salinity of average sea water (table 4). Certainly, calcium, magnesium, and potassium are present in sufficient 

quantities in the bay water to cause some flocculation of the humate 

carried in by the stream; and possibly the flocculation reaction observed in the laboratory on addition of, for example, CaCl2 solution 

to dissolved humates closely simulates that which takes place when 

the tea- to coffee-colored stream water comes into contact with the 

bay water. These waters were not analyzed for iron and aluminum, 

which may also be partly or largely responsible for humate flocculation 

in this part of Florida, as suggested by the spectrographic analyses 

of the humate.

TABLE 5. Partial chemical analyses, in parts per million, of a stream water and 

brackish water from Choctawhatohee Bay that are involved in transportation 

and deposition of humate

[K.A. Gardner and 8. J. Bucker, analysts]

Sodium. _______ _____________ 

Calcium __ _ ________ _ _._ _ __

Magnesium __ ____________________

Potassium _ ______________________

Chloride. __-__--_________-__-____-

Bicarbonate

Specific conductance G_mhos)__ __ __

862-36

Water from small

stream, 35 ft 

from south

shore of

Choctawhatchee

Bay

19

1.5

2.1

1.0

32

1

134

862-37

Brackish bay

water, 30 ft from 

south shore of

Choctawhatchee

Bay

3,000

148

287

98

5,240

61

15, 500

Average sea 

water 1

10, 556

400

1,272

380

18, 980

140

1 Sverdrup, Johnson, and Fleming (1042, p. 173,195).

SUMMARY AND CONCLUSIONS

An attempt has been made in this paper to describe and define in 

terms useful to both the geologist and chemist an environment and
B26 CONTRIBUTIONS TO GEOCHEMISTRY

the applicable genetic processes of modern humate deposition. The 

primary objective has been, however, to convey to geologists the need 

to recognize humate as a type of carbonaceous material in the sediments and rocks of their areas of study and to consider the potential 

significance of humate in their interpretations of environments of 

deposition. Thus, in summary:

1. A large fraction of carbonaceous material in many sedimentary 

rocks, particularly those deposited in a coastal environment, 

probably was transported asr dissolved or colloidally dispersed 

humic substances in water.

2. These dissolved and colloidal organic materials, which are largely 

derived by leaching from decaying plant material at the surface, 

may be transported and deposited syngenetically with finegrained sediment at the bottom of a body of water, such as a river, 

lake, bay, or ocean; or they may be deposited as a penecontemporaneous or epigenetic interstitial filling by downward or lateral 

percolation into a porous and permeable sediment such as a beach 

or dune sand.

3. This soluble and colloidal material, when deposited in sediment, 

is herein called humate.

4. Humate is formed when the soluble and colloidal humic material 

in surface or subsurface water enters a different physical-chemical 

environment and precipitation or flocculation occurs. For example, humate is deposited when, it combines with waters containing dissolved ions such as aluminum, iron, and .magnesium, 

which are common in sea and brackish waters, on complexing with 

clay colloids, or on combining with waters of .pH less than 5.

5. Humate is abundant, and is widely .distributed in Quaternary sediments along the Gulf of Mexico coast of the Florida panhandle. 

It accumulates in and near bays and sounds of brackish water, 

particularly in beach and dune sands.

6. This Florida humate commonly impregnates or cements sand to 

form, a dark brown to black layer a few feet thick, but composes 

only 1-8 percent of the sediment.

7. The average ash-free composition of the humate, in percent, is 55.0 

carbon, 4.4 hydrogen, 38.5 oxygen, 1.4 nitrogen, and 0.7 sulfur, 

which is comparable to the composition of humic acids derived 

from soil, of yellow coloring matter in lake water, of lignin, of 

:dopplerite, and, in aTery general way^ of some peat and lignite 

deposits.

8. The Florida .humate has .a larger, suite and greater amount of trace 

metals than do the associated detrital sediments, but the mietals 

are not in abnormally high concentrations when compared with
HUMATE IN COASTAL SANDS OF NORTHWEST FLORIDA B27

the content in other humates and ancient humic substances in 

rocks. Of interest, particularly when considering the mobility of 

humate, is that humate has the capacity to sorb large amounts of 

metals (Mortensen, 1963, p. 180; Swain, 1963, p. 133), such as 

iron, copper, and uranium, and potentially can form an ore deposit on final deposition (Vine, Swanson, and Bell, 1958; Gate, 

1960, p.425).

9. Humate can be compared to hydrocarbons in that both have a biologic origin and both migrate or are transported with water 

through sediments. However, chemically they are quite distinct humate is a high-oxygen low-hydrogen substance, is coallike in composition, is insoluble in benzene, and is transported in 

a soluble or colloidal form in water. Also, the modes and sites of 

accumulation of the two in a sediment greatly differ the deposition of humate is controlled by the spatial position of a physicalchemical difference in surface or subsurface waters, commonly 

irrespective of sediment type or structure, whereas most hydrocarbons, being immiscible in water, are transported, physically 

separated, and concentrated as distinct gaseous or fluid substances 

in some structural or stratigraphic trap. Though these differences between humate and hydrocarbons may be oversimplified, 

no evidence produced during this study is construed as support 

for the theory that humate is a progenitor of petroleum hydrocarbons.

10. Many questions about the origin and geochemistry of humate, as 

a group of natural carbonaceous substances in either modern or 

ancient sediments, still remain unanswered. The biochemical 

progenitors of humate, and the processes of degradation, deposition, and diagenesis of humate are still far from being understood, but this lack should not deter geologists from recognizing 

humate and its significance in geologic studies.

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