196 THE FLORIDA ANTHROPOLOGIST

2006 VoL. 59(3-4)

 

Table 2. Surface textures of Miami Circle pumice specimens.

    
 

p82 TB
PG TS
g) P| 10
dense & cha | 8

Pt

popcorn-like

Surface texture
tube pumice

   

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Table 3. Inclusions in Miami Circle pumice specimens.

Inclusions Count
of Total
phenocrysts

autoliths

xenoliths

none observed

 

Roundness

well-rounded
rounded

sub-rounded
sub-aneular

not determinable

 

z
3 >

Powers (1989) and are a means to accurately describe the shape
of a geological specimen (also see Pettijohn 1975, and Skinner
2000). Pieces were usually described as well-rounded, round-
ed, sub-rounded, sub-angular, or angular (Table 4). Pumice
deposited after eruption is typically angular, though most intact
examples within the study set were rounded. It is unclear if this
is due to transportation via water or from use. Guppy
(1917:164) notes that examples of pumice washed ashore in the
Turks Islands are usually rounded cobbles, suggesting that this
may be the typical form encountered in specimens recovered
from beach drift.

Shape: Sphericity

The generalized sphericity of each pumice clast was
described. Sphericity standards are from Power (1989, also see

Pettijohn 1975, and Skinner 2000). Terms used to describe |

sphericity include discoidal, sub-discoidal, spherical, sub-
prismoidal, and prismoidal (Table 5). Often times, fragmentary
specimens could not be described for sphericity. Most of the
specimens from the Miami Circle were described as sub-
discoida! or spherical. Powers (1989) states that geological
particles are usually discoidal, rodlike (prismoidal), or spheroi-
dal when they initially break out of or weather from parent
materials. Weathering and abrasion tend to produce more
spherical shapes. It is unclear if the pumice clasts examined
during this study reached their rounded, spherical forms from

use or from wave action and weathering.
Modification

Evidence for artifactual use, like grooves, flat sur-
faces, cup-shaped depressions, facets, or perforations
were noted (Figures 7 and 8). Forty of the pumice clasts
from the Miami Circle exhibit one or more of these forms
of modification. Examples from other sites had similar
modifications (see Table 1). These artifacts with clear
evidence of use are described below in more detail.

Shallow Grooves (n=7). Shallow grooves are linear,
often fusiform, depressions that are about as wide as they
are deep. Diameters of these grooves range from 0.2 to
1.0 cm. Shallow grooves may result from use of the
pumice clasts in polishing bone artifacts. The shape and
size of the shallow grooves corresponds favorably with
many of the mammal long bone implements from the
Miami Circle (Wheeler 2004a). Shallow grooves often
occur with other forms of modification, like cup-shaped
depressions. In some cases only one groove is present,
while multiple grooves (2 to 3) are common. These
grooves usually are parallel to one another and suggest
these artifacts were used like hones to polish or sharpen
bone artifacts. Pumice artifacts from other sites also
exhibit shallow grooves. Two clasts of pumice from
excavations at the Brickell Point site (8DA98), adjoining
the Miami Circle property to the south, have combina-
tions of shallow grooves and cup-shaped depressions. A
discoidal clast from the Granada site (8DA11) also
exhibits a single shallow groove.

Deep Scoring (n=8). Deep score marks are similar to shallow
grooves, but tend to be narrower and deeper. Score marks
range from 0.1 to 0.3 cm in width, but may be as deep as 0.4 to
0.5 cm. These score marks may have resulted from abrasion
with cordage. Cords may have been tied around some clasts,
causing the deep scoring, or cordage may have been used to
saw large clasts into smaller pieces.

Cup-shaped Depressions (n=5). Cup-shaped depressions,
usually occupying an entire surface of a rounded, spherical
clast, may have been the result of polishing rounded wood
surfaces. Cup-shaped depressions were noted on clasts from
other sites as well, including the Higgs site (8IR24), Brickell
Point (8DA98), and the Honey Hill/Stadium site (8DA411).
The example from the Honey Hill/Stadium site (8DA411) has
the remnants of a perforation at one end (Figure 9).

Flat Surfaces (n=16). Flat surfaces are often found on dome-
shaped clasts. These dome-shaped pieces with one flattened
surface are suggestive of sanding blocks. It is possible that
these pieces were used in finer sanding and polishing of wood.
Historically, pumice has been used in polishing and refinishing
of lacquered wood surfaces, frequently in the technique known
as “French polishing” (Hayward 1975; Matthew 1955). Pumice
also has been used in Europe for polishing ivory and some
metals (Timothy Burke, personal communication, 2002; also