1. PETROGLYPH CHRONOLOGY
IN SOUTHEAST COLORADO
©1995, Peter Faris
Southwestern Lore, Vol. 61, No. 1,
pages 7-35 .
Funded by Colorado Endowment for the Humanities
Grant #R070-0992-038.
Photo: Jeannie H. Gibson, 1991

2. Previous Research
• G. J. Anderson, Fort Lyon, CO, / Charles Darwin – 1874.
• E. B. Renaud, University of Denver – 1931 to 1936.
• Robert Gordon Campbell, Chaquaqua Plateau in Bent and Las
Animas counties – 1969 thesis, C. U.
• Joe Ben Wheat – 1954.
• University of Denver, 5BN7 – 1971.
• Colorado Archaeological Society, 5LA1115 – 1978.
• Colorado Archaeological Society, 5LA5781 – 1984.
• Fort Carson/Pinon Canyon Maneuver Site, Sally Cole – 1980s.
• Dr. Lawrence Loendorf, P.C.M.S. – 1980s to present.
• Denver Chapter/CAS , 5BN7 and other sites – Late 1980s.
• McGlone, Leonard, etc. – Late 1980s to 1993.

3. Study Area – Baca, Bent, Las Animas, Otero,
and Prowers Counties, Colorado.

4. View of Picketwire Canyonlands.
Photo: Peter Faris, 1999

5. Cultural Periods in Southeast Colorado
• Paleoindian Stage (ca. 11,700 – 7500 B.P.)
• Archaic Stage ca. (7500 – 1800 B.P.)
• Early Archaic period (7500 – 5000 B.P.)
• Middle Archaic period (5000 – 3000 B.P.)
• Late Archaic period (3000 – 1800 B.P.)
• Ceramic Stage (1800 – 250 B.P.)
• Historic Stage (250 B.P. – present)

6. ROCK ART STYLES IN
SOUTHEASTERN COLORADO
PECKED ABSTRACT (PAB)
PECKED REPRESENTATIONAL STYLE (PRP)
PURGATOIRE PETROGLYPH STYLE (PPG)
GREAT PLAINS REGIONAL (RGN)
PLAINS BIOGRAPHIC STYLE (PBG)
OGAM-LIKE STYLE (OGM)

8. ROCK ART DATING
Before the 1990s dating rock art depended
on relative methods.
• Stratigraphy
• Association
• Stylistic comparison
During the 1990s rock art dates based upon
cation ratio analysis by Dr. Ronald I. Dorn
became available in published sources.

10. PECKED ABSTRACT STYLE
• Includes pecked
curvilinear and pecked
rectilinear elements.
• Elements include dots,
circles, curved lines,
angular shapes, rakes,
lines, and others.
• Often display signs of
considerable age. Dates
range from 5000 B.P. to
1100 B. P.

11. Typical Pecked Abstract Elements found in
Southeastern Colorado
Hicklin Springs, 5BN7, Bent County,
Colorado. Photo: Peter Faris, 1994

12. However, there are other possible
explanations.
Tarantula, Picketwire
Canyonlands, 1994
Centipede, Vogel Canyon,
1993

13. PECKED REPRESENTATIONAL STYLE
• Pecked figures, usually
quadrupeds.
• Figures totally pecked,
sometimes stipple
pecked.
• Figures usually found in
groups.
• Dates range from 3500
B.P. to 1500 B.P.
Photo: Peter Faris, 1986.

14. Pecked Representational Style, Picketwire
Canyonlands, near Split Rock.
Photo: Peter Faris, 1992.

15. PURGATOIRE PETROGLYPH STYLE
• Frontal view figures with
spread fingers, often with
knobby knees.
• Facial features/headdresses
usually absent.
• Figures often have an open
space in the torso.
• Dates range from 1500 B.P.
to 500 B.P.
Salt Arroyo, Purgatoire River, Bent County. Photo: Peter Faris, 1991.

16. Purgatoire Petroglyph Style. Excellent quality
solidly pecked figures. Pat Canyon, Baca
County. Photo: Peter Faris, 1986.

17. GREAT PLAINS REGIONAL STYLE
• Great Plains and Rio
Grand style elements.
• Horned heads, animals
with hearlines, pecked
outline or totally
pecked figures.
• 700 B.P. to 300 B.P.
Figure 8, 5BN7.
Photo: Peter Faris

18. Rio Grande Style Elements
Purgatioire River Canyon, Otero County
Photo: Peter Faris, 1966

19. PLAINS BIOGRAPHIC STYLE
• Early Plains Biographic
style (James Keyser’s
Ceremonial style), ca. 990
B.P. to 290 B.P.
• Deeply incised rather than
pecked.
• Plains Biographic style, ca.
220 B.P. to 100 B.P.
• Cation-ratio dating
ineffective with dates of
less then 300 B.P.
Figure with spears, Picture Canyon, Baca County. Photo: Peter Faris, 1986.

20. More Early Plains Biographic Style Art.
Figure deeply incised and carrying weapons. Struck by arrow
in the torso. Photo: Peter Faris, 1987.

21. Left side of previous panel
Photo: Peter Faris, 1987.

22. Late Plains Biographic Style art.
Post contact or historic period. Shallowly incised lines. Photo:
Peter Faris, 1986.

23. Late Plains Biographic Style art.
Box Canyon site, 5LA8464, Picketwire Canyonlands.
Photo: Peter Faris, 1999

24. TALLYFORM (OGAM-LIKE) STYLE
• Groups of lines or
parallel markings
resembling counts
or tallies.
• Ca. 2975 B.P. to 750
B.P.

25. CULTURAL PERIODS AND DATED ROCK ART STYLES IN
SOUTHEAST COLORADO

26. ANALYSIS

27. Conclusions
• The Pecked Abstract (PAB) style (4675-1300
B.P.) and Pecked Representational (PRP) style
(3500-1500 B.P.) cover nearly the entire span
of the Middle Archaic through Early Ceramic
periods.
• The Tallyform (Ogam-like) (OGM) style (2975-
750 B.P.) extends from the Late Archaic
period through the middle of the Middle
Archaic period.

28. • The Purgatoire Petroglyph (PPG) style (1500-
500 B.P.) falls conveniently within the Early
and Middle Ceramic periods.
• The Regional (RGN) style (700-300 B.P.) falls
within the Middle and Late Ceramic periods
and probably represents the early stages of
the Plains Biographic style.
• The Plains Biographic (PBG) style (<300 B.P.)
falls within the Late Ceramic and Historic
periods.

29. In May 24 – 26, 1997, the American
Rock Art Research Association held its
annual conference in La Junta. During
that meeting Dr. Ronald I. Dorn
publicly disclaimed all his previous
dating results based upon possible
flaws in assumptions that needed to
be relied upon for accuracy.

30. Recommendations
Other dating strategies can be used to approach the
same questions.
ABSOLUTE:
• Carbon14 Dating of organics in the desert varnish by
Accelerator Mass Spectrometer (AMS) - an
expensive proposition.
RELATIVE:
• Stratigraphy - at certain locations in the canyon of
the Picketwire the older petroglyphs are higher on
the cliff.
• Association – specific symbols found together in
multiple locations.

31. Photo: John Rudolph, 1991.