REPORT OF INVESTIGATION NO. 107
A SEDIMENTOLOGICAL ANALYSIS OF SEAGRASS BED
SUBSTRATE FROM BAY COUNTY, FLORIDA
Daniel C. Phelps, (P.G. # 1203), Michelle M. Lachance and
James G. Sparr
TABLE OF CONTENTS
Report




Introduction
Sediment Sample Processing
Data Analysis
References Cited
Tables


Table 1 - Sieve Set Used in Grain Size Analysis
Table 2 - Sample Index
Figures



Figure 1 - Site Location Map
Figure 2 - Frequency Plot of Samples for Tyndall Site
Figure 3 - Frequency Plot of Samples for Spanish Shanty Site
Appendices
 Appendix A - Powerpoint Presentation
INTRODUCTION
IIn May 2007 the Florida Geological Survey’s Coastal Research Program (FGS-CRP) was contacted by the
Florida Fish and Wildlife Conservation Commission (FWC) regarding the granulometric processing of
seabed sediment samples as part of a project to repair prop scarring in sea grass beds. The intent was to
characterize the nature of the seabed sediments in the affected area so that sediment matching could
be facilitated. Personnel from the FDEP’s Division of Recreation and Parks (FDEP-DRP), at the request of
the FWC, collected a total of 13 seabed samples from two locations in the state waters of Bay County.
Six samples were collected from the first site and seven from the second. These two sample locations
are shown on Figure 1.
SEDIMENT SAMPLE COLLECTION
The sediment samples were collected by the FDEP-DRP on May 29, 2007 from a kayak. Location
coordinates were established using a Garmin Etrex Legend GPS receiver. Samples were collected at
high tide by scooping individual surficial sediment samples from various scars at the two locations
selected. Samples were secured in zip lock bags as they were being collected.
SEDIMENT SAMPLE PROCESSING
The sieve nest used in sample processing by the FGS-CRP is illustrated on Table 1. All granulometric
analyses were conducted using the general guidelines of the American Society for Testing and Materials
(ASTM) (2000a, 2000b) and specific procedures advanced by the FGS sedimentology laboratory (Balsillie,
1995, 2002a, 2002b, Balsillie and Tanner, 1999; Balsillie, et al. 1999; Balsillie et al. 2002a; Balsillie et al.
2002b; Balsillie and Dabous, 2003). Samples were oven dried, initially weighed, then wet sieved through
a 230 sieve (0.63 mm or 4 phi), oven dried again and reweighed with the weight loss being assigned to
the fine fraction. The sample was then dry sieved with the portion of the pan fraction obtained during
dry sieving also assigned to the fine fraction. No samples exhibited a sufficiently significant percentage
of fines to support further characterization using the methodology of Folk (1974) and Galehouse (1971).
Cumulative grain size distribution curves reflect the total grain size distribution (GSD) of each sediment
sample. The weight of the fine fraction, consisting of the weight loss from wet sieving plus weight of the
fraction passing through the sieve nest to the pan was, as noted above, assigned to the finer than 4 phi
fraction.
DATA ANALYSIS AND RESULTS
GSD curves are presented for the seabed samples both individually and collectively for the two site
locations shown on Figure 1. This data can be accessed from Table 2. Figures 2 and 3 illustrate the
collective frequency curves for site one, Tyndall, and site two, Spanish Shanty, respectively.
At site one, Tyndall, the six samples collected ranged in weight from 37.406 to 79.944 grams. For those
six samples the minimum mean grain size was 1.899 phi (0.2681 mm), and. the maximum mean grain
size was 2.055 phi (0.2407 mm). The average grain size of those samples was 1.969 phi (0.2554 mm).
Munsell colors for the samples were 5Y 7/1 and 5Y 7/2.
At site two, Spanish Shanty, the seven samples collected ranged in weight from 30.556 to 93.320 grams.
For those seven samples the minimum mean grain size was 1.912 phi (0.2658 mm) and the maximum
mean grain size was 1.939 phi (0.2607 mm). The average grain size of those samples was 1.926 phi
(0.2631 mm). Munsell colors for the samples were 5Y 7/2, 5Y 8/1 and 2Y 8/2.
A PowerPoint Presentation has been prepared that summarized these finding. It is provided as
Appendix A.
REFERENCES CITED
American Society for Testing and Materials, 2000a, Standard test method for particle-size analysis of soils:
West Conshohocken, Annual Book of ASTM Standards, American Society of Testing and Materials
International, v. 4.08, p. 10-16.
American Society for Testing and Materials, 2000b, Standard guide for statistical procedures to use in
developing and applying test methods: West Conshohocken, Annual Book of ASTM Standards, American
Society of Testing and Materials International, v.14.02, p. 583-588.
Balsillie, J. H.,1995, William F. Tanner on environmental clastic granulometry: Florida Geological Survey
Special Publication No. 40, 145 p.
Balsillie, J. H., 2002a, Analytic granulometry tools: Florida Geological Survey Web site:
http://www.dep.state.fl.us/geology/geologictopics/analytic_gran_tools/analytic_gran.htm
Balsillie, J. H., 2002b, Red flags on the beach, part III: Journal of Coastal Research, v. 18, p. iii-vi.
Balsillie, J. H., and Dabous, A. A., 2003, A new type of sieve shaker; the Meinzer II, comparative study with
Rotap technology: Florida Geological Survey Open File Report No. 87, 93 p.
Balsillie, J. H., and Tanner, W. F., 1999, Suite versus composite statistics: Sedimentary Geology, v. 125, p. 225234.
Balsillie, J. H., Tanner, W. F., and Williams, H. K., 1999, Sticky grain occurrences in sieving: Florida Geological
Survey Open File Report No. 79, 15 p.
Balsillie, J. H., Dabous, A. A., and Fischler, C. T., 2002a, Moment versus graphic measures in granulometry:
Florida Geological Survey Open File Report No. 84, 85 p.
Balsillie, J. H., Donoghue, J. F., Butler, K. M., and Koch, J. L., 2002b, Plotting equation for Gaussian percentiles
and a spreadsheet program application for generating probability plots: Journal of Sedimentary
Research, v. 72, p. 929-933.
Folk, R. L., 1974, Petrology of Sedimentary Rocks: Austin, Hemphill, 182 p.
Galehouse, J. S., 1971, Sedimentation analysis: in R. E. Carver, ed., Procedures in sedimentary analysis: New
York, Wiley-Interscience, p. 69-94.
Table 1
Table 1
Sieve Set Used in Grain Size
Analysis
Sieve
Mesh
Phi Size
Number
Size(mm)
5
-2.00
4.00
6
-1.75
3.35
7
-1.50
2.80
8
-1.25
2.36
10
-1.00
2.00
12
-0.75
1.70
14
-0.50
1.40
16
-0.25
1.18
18
0.00
1.00
20
0.25
0.85
25
.50
0.71
30
0.75
0.60
35
1.00
0.50
40
1.25
0.425
45
1.50
0.355
50
1.75
0.300
60
2.00
0.250
70
2.25
0.212
80
2.50
0.180
100
2.75
0.150
120
3.00
0.125
140
3.25
0.106
170
3.50
0.090
200
3.75
0.075
230
4.00
0.063
Sieve Nest
click photo to enlarge
Table 2 - Sample Index
Tyndall (TYN) Samples:
 TYN-1
 TYN-2
 TYN-3
 TYN-4
 TYN-5
 TYN-6
 Combined Analysis
Spanish Shanty (SS) Samples:
 SS-1
 SS-2
 SS-3
 SS-4
 SS-5
 SS-6
 SS-7
 Combined Analysis
Figure 2
Frequency Plot of Samples for Tyndall Site
To view additional data, please view the Sample Index
Figure 3
Frequency Plot of Samples for Spanish Shanty Site
To view additional data, please view the Sample Index