Mystery of the maya collapse

1. Mystery of the Maya Collapse
from Curtis et al. 1997
Scientific Authorship: David Hodell & Lisa M. Lixey
As Interpreted by M. Anderson, 2007

2. Discovery of the Maya
Maya cities were deserted, hidden by trees, and virtually
unknown until rediscovered in 1839 by a rich American
lawyer named John Stevens, who, under appointment by
President Martin Van Buren, explored and documented
the existence of 44 Mayan sites and cities.
 Stevens wrote: “ The city was desolate. No remnant of this
race hangs round the ruins….It lay before us like a
shattered bark in the midst of the ocean, her mast gone,
her name effaced, her crew perished, and none to tell
whence she came, to whom she belonged, how long her
journey or what caused her destruction….

3. Discovery of the Maya
….Architecture, sculpture, and painting, all of the arts which
embellish, has flourished in this overgrown forest; orators,
warriors and statesman, beauty ambition and glory have
lived and passed away, and none knew that such things
had been or could tell of their past existence….Here was
the remains of a cultivated, polished, and peculiar people,
who had passed through all the stages incident to the rise
and fall of nations; reached their golden age, and
perished….

4. Discovery of the Maya
….We went up to their desolate temples and fallen alters; and
wherever we moved we saw the evidence of their taste,
their skill in arts….We called back into life the strange
people who gazed in sadness from the wall; pictured them,
in fanciful costumes and adorned with plumes of feathers,
ascending the terraces of the palace and the steps leading
to the temples….overgrown with trees for miles around, and
without even a name to distinguish it.”

5. Links between
Climate
Change and
Society
Collapse
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Copan mound
Our society is increasingly interested in the consequences
of future climate and environmental changes, as well as the
role that humans play in these changes.
Human civilizations throughout history have affected the
environment (and perhaps influenced climate) through
deforestation, agriculture, urbanization and industrialization.
In turn, climate events such as droughts, floods, and
hurricanes have impacted ancient cultures, both socially
and economically.

6. Maya Civilization
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The Maya civilization is
one of the best-known
ancient civilizations of
Mesoamerica.
The Maya originated
around 2600 BC in the
Yucatan peninsula and
rose to a cultural and
geographical
prominence in the
classic period (250900 A.D.) when they
occupied present-day
Chiapas, Guatemala,
Belize, Southern
Mexico and Western
Honduras.

7. 
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Maya Culture
By borrowing the ideas and tools
of neighboring civilizations, the
Maya were able to develop
sophisticated concepts in the
disciplines of astronomy and
mathematics.
They used this knowledge to
construct a calendar system and
implemented the mathematical
concept of zero.
The Maya developed a written
language through the use of
hieroglyphics and were known
for their ceremonial architecture
that included temple-pyramids
and residential palaces.
The Maya were also skilled
farmers, potters, and weavers
trading and distributing goods
with distant peoples.
Copan Great Hieroglyphic Stairway

8. 
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The Mayan golden age
lasted five centuries from
300 to 800 AD.
At 800 AD they stopped
building temples, declined
and became fragmented
in competing states.
These were easy prey for
invading forces from the
north such as the Toltec.
The Toltecs became the
ruling elite of the Maya in
the post classic period.
Toltec gods were added
to the Maya pantheon but
the Toltecs were
absorbed as they leaned
to speak Yucatec Maya.
Maya Culture
Copan decoration on Temple of Inscriptions

9. 
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The Maya were organized in
city states, sharing the same
beliefs and deferred to priests
who derived power from their
knowledge of astronomy,
mathematics and numerology.
The Maya were aware of the
passage of time.
They recorded some dates on
stelae and probably much
more in books that are lost
now because Spanish Catholic
priests destroyed them to
eradicate "pagan beliefs".
To retrace the history of the
Maya we have to rely on
whatever clues we can find in
what is left of archaeological
sites that the Spanish did not
plunder or destroy.
Maya Culture
Copan

10. Tikal
Tikal Temple 1
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Deep within the tropical rainforests of Guatemala lies Tikal,
one of the largest cities of the Maya civilization.
Serving as an administrative, ritual and cultural center for
the surrounding urban and agricultural regions, Tikal was
home to large populations of people.
During the time period between 600 and 800 A.D., Tikal's
population grew to as many as 60,000 citizens, making the
population density of the city several times greater than the
average city in Europe or America during this time.

11. Tikal
Ancient Tikal © Holdell
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The city of Tikal occupied a six-square mile area and
included as many as 10,000 individual structures, ranging
from temple-pyramids to thatched-roof huts.
The temple-pyramid was by far the most impressive of the
architectural feats and towered above all other structures of
the Maya city.
Built from hand-cut limestone blocks, the temple-pyramids
contained only one or two narrow rooms and mainly was
used for ceremonial purposes.

12. Tikal
Tikal Palace © Holdell
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The Maya also built low, multi-room buildings, called
palaces, that were thought to have served a residential
function for the ruling class. This palace is also from Tikal.

13. Tikal
Tikal Temple of the Masks ©
Holdell

14. Maya Cultural Periods
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The Pre-classic Period: 2000 BC
to 250 A.D.
The Classic Period: 250 A.D. to
900 A.D.
The Post-classic Period: 900
A.D. to the time of Spanish
Conquest beginning in 1524 A.D.
The Maya culture flourished
during the late Classic Period
from @ 600 to 800 A.D.
The Maya Classic Collapse
civilization occurred between 800
and 900 A.D.
At this time, all of the large
Classic sites in the southern area
were abandoned, never to be reoccupied to the same extent as
during the Classic Period.
Chart: Coe © 1987

15. Mystery of the Maya Collapse
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For over a decade, archaeologists
have been trying to unlock the
mystery surrounding the collapse
of the Ancient Maya civilization.
Did human-induced sociopolitical or
ecological change cause the
collapse of this highly advanced
Mesoamerican civilization, or could
natural climate variability of the
Yucatan Peninsula have
contributed to the collapse?
Paleoclimatologists are studying
the climatic history of this region to
provide archaeologists with the
climate context in which the Maya
civilization evolved, flourished and
ultimately collapsed.
Tikal

16. Mystery of
Maya
Decline
Copan Popol Nah Council House
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The cause of the Maya decline remains their greatest
mystery.
Their civilization was not destroyed by an overwhelming
outside force.
The Maya power disintegrated from within.
Many hypotheses have been proposed: overpopulation,
famine, epidemics, civil disorder, or could the common
people just stopped believing in the dogma the elites were
using to establish their power and justify their excesses?

17. Sociopolitical Causes of Collapse
The sociopolitical
causes include:
 peasant revolts
resulting in the
overthrowing of the
elite class
 inter-site warfare
between Maya citystates
 invasions by peoples
from outside the
Maya civilization
 failure of centralized
political authority
Copan sacrificial alter

18. Natural Causes of Collapse
Natural causes include
factors such as:
 soil exhaustion due to
slash-and-burn
agriculture
 water loss and erosion
of topsoil evident by
increased
sedimentation in lakes
 natural disasters such
as earthquakes and
hurricanes
 climatic change
 disease
 insect infestations
 overpopulation
Copan Great Ball Court

19. Natural Causes
of Collapse
Water deficit on the Yucatan © NOAA
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When examining the natural causes that could have incited
or enhanced the collapse, a further set of both humaninduced and natural climatic factors of the Yucatan
Peninsula need to be considered.
Some scientists theorize that the paleoclimate of the region
was not only different than the present day climate, but that
the natural climatic variability of the past could have
included a period of intense drought that occurred at the
time of the Classic Maya Collapse.

20. Symptoms of the Collapse
Copan East Plaza with Temple of Inscriptions and alter Q; R: Copan East Plaza
and Temple 11 with Popol Nah.
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Rapid depopulation of the countryside and ceremonial
centers in 50 to 100 years,
Abandonment of administrative and residential structures,

21. Symptoms of the
Collapse
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Cessation of: building construction,
carving of sculptured monuments,
manufacture of pottery, stonework,
jade carvings, Classic calendar and
writing systems.
Above: Copan temple; Above R: corbeled
block-work used by Maya; lBelow R:
Copan sculpture.

22. Yucatan Modern Climate
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Before studying the paleoclimate of
the region, it is important to understand
the region's modern climate.
Temperature is uniformly warm on the
Yucatan Peninsula with a mean annual
temperature of 25o C.
Precipitation increases from north to
south with minimum values of 500
mm/yr along the NW coast to a
maximum of 2500 mm/yr in the
southern lowlands.
Rainfall is highly seasonal with the
rainy season occurring in the summer,
May through September, and the dry
season during winter, October through
April.
All of the Yucatan is marked by an
annual water deficit that is lowest in the
southern Yucatan and highest along
the NW coast.
Koeppen Climate classification
© NOAA

23. Lake Sediments
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The raw material for
paleoenvironmental studies is
sediment that accumulates in an
ordered manner through time and
records changes in past climate
conditions.
The sediments are analogous to a
magnetic cassette tape recording,
and the challenge for
paleoclimatologists is to "play
back" the tape.
Fossil pollen preserved in lake
sediments are often used to
reconstruct vegetation changes
that can be influenced by climate.
Sediment core from Lake
Chichancanab

24. Lake Sediment Cores
Scientists reconstructed the
past climate of the Maya
civilization by studying lake
sediment cores on the Yucatan
Peninsula.
The first area of study, Lake
Chichancanab, is located in the
center of the Yucatan.
Lake Chichancanab is a long
(26-km), narrow (2 km) lake,
consisting of a series of basins
that are connected during high
water level.
Jason Curtis holding core form Lake
Chichancanab

25. Lake Chichancanab
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Sediment cores
were collected
from the central
basin in a water
depth of 6.9 m.
The lake lies in a
fault depression
caused by
normal faulting.
The steep hills
on the eastern
side of the lake
represent the
fault line.

26. Lake Sediments
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Pollen cannot be used to
reconstruct climate during the
Classic Period because the
Maya severely altered regional
vegetation through clear cutting
of the forest for agricultural
purposes.
It would be impossible to tell,
whether a given vegetation
change was caused by climate
or human agricultural activity.
Because of this, scientists rely
upon geochemical (elemental
and isotopic) evidence for
climatic change found trapped in
the shells of tiny Crustacea
called ostracods.

27. Oxygen Isotopes
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One of the most important tools used to
reconstruct the ratio of evaporation to
precipitation is oxygen isotopes .
Lake water (H2O) contains both the light
isotope (16O) and heavy isotope (18O) of the
element oxygen.
When water evaporates, the lighter
isotope (H216O) evaporates at a faster rate
than the heavier isotope (H218O) because it
has a higher vapor pressure.
The reverse happens when water
condenses. As long as evaporation
equals precipitation over the lake, the
lake is at a steady state and the ratio of
18
O to 16O will be constant.
However, if climate becomes drier and
evaporation exceeds precipitation, the
lake volume will be reduced and the ratio
of 18O to 16O in lake water will increase.
Illustration From Curtis,
et al © 2007

28. Oxygen Isotopes
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Alternatively, under wet climatic
conditions, the lake level will rise
and the ratio of 18O to 16O will
decrease. In closed basin lakes, the
ratio of 18O to 16O in lake water is
controlled mainly by the balance
between evaporation and
precipitation.
The 18O to 16O ratio of lake water is
recorded by aquatic organisms,
such as gastropods and ostracods
that precipitate shells of calcium
carbonate (CaCO3).
Scientists can measure the 18O to 16O
ratio in fossil shells in sediment
cores to reconstruct changes in
evaporation/precipitation through
time, thus inferring climatic change.
Illustration © From Curtis,
et al © 2007

29. Hydrology: Closed Basin Lakes
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This study consisted of
taking sediment cores
from two different lakes
centrally located on the
Yucatan.
Both Lakes
Chichancanab and
Punta Laguna are
considered to be
closed-basin lakes.
The geology of
Yucatan is karst
(porous limestone),
many of the lakes are
perched above the
water table and
isolated hydrologically
by clay-basin seals.
Illustration From Curtis, et al © 2007

30. 
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Closed-basin lakes have
simple water budgets, and
typically receive water by
precipitation, slope wash,
and groundwater seepage,
while losing a majority of
their water through
evaporation.
Therefore the lake
volume, dissolved solute
concentrations and oxygen
isotopic ratios are largely
controlled by the ratio of
evaporation to
precipitation.
This characteristic makes
closed-basin lakes
climatically sensitive to the
changing conditions of
evaporation or
precipitation.
Closed Basin
Lakes
Illustration From Curtis, et al © 2007

31. Oxygen
Isotope /
Rainfall
Illustration From Curtis, et al © 2007
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This bar chart shows measurements of the oxygen
isotopic ratio of modern rainfall and groundwater (blue and
magenta) compared to lake water from Chichancanab
(white) and Punta Laguna (yellow).
The results indicate that a significant amount of water
received by Lakes Punta Laguna and Chichancanab was
lost to evaporation annually, thereby enriching the lake
water in 18O.

32. Sediment Cores
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To retrieve sediment cores
from both lakes, two different
coring systems were used.
For the top most sediments
that are water-saturated and
oozy, a mud-water interface
corer, consisting of a clear
polycarbonate tube (125 cm
by 7 cm) was used.
Deeper sections of the core
that occur past the mudwater interface are retrieved
in 1 meter intervals using a
square-rod piston corer.
Similar modified Livingston coring
device being used in Trinidad.

33. Coring Site #2
Holdell
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The second lake from which scientists retrieved sediment
cores was Lake Punta Laguna, located in the northeastern
part of the Yucatan Peninsula about 20 km N-NE of Coba,
a major Mayan archaeological site.
Punta Laguna consists of three interconnected basins, each
with a maximum depth of about 20-m.
The coring site was located in the far basin in a water depth
of about 6.3-m.

34. Sedimentation Rates
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When the cores are returned to the lab, they are split
in two halves. One-half of the core is sampled and
the other half is archived for future use.
The core that was sampled from Lake Chichancanab
had a total length of 4.9 m with a basal radiocarbon
age of 9000 years BP.
The sedimentation rate averaged about 0.5 mm per
year.
The core was sampled continuously at 1-cm intervals
over its length.
A 1-cm sample in the Lake Chichancanab core
represents about 20 years of deposition.
The sedimentation rate determines the temporal
resolution of study and as a result, scientists are able
to reconstruct climatic changes that lasted for
multiple decades or longer.
The sediments of Chichancanab consisted of
alternating layers of organic matter, calcite, and
gypsum.

35. Punta Laguna Core
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The total core length from Punta
Laguna was 6.3m with a basal
age of 3300 years.
The sedimentation rate averaged
2 mm/year, which is about four
times greater than the
sedimentation rate in the core
from Chichancanab.
A 1-cm sample for the Punta
Laguna core represents only 5
years of deposition, permitting the
resolution of much shorter climatic
events.
Sediments in the Punta Laguna
core are composed almost
Above and previous cores are
entirely of calcium
similar representation taken from
carbonate(CaCO3).
recent Trinidad expedition.

36. Dissolved
Ions in Lake
Water
Diagram From Curtis, et al © 2007
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This pie diagram illustrates the dissolved ions in lake water
from Lake Chichancanab.
It is rather salty with total dissolved solids of 4011 mg/L.
Chichancanab in Yucatec Mayan means "little sea", which is
an appropriate name in light of its saline, sulfate-rich waters.
The dominant anion is sulfate (SO4) and the dominant cation
is calcium (Ca).
Chichancanab is saturated for calcium carbonate and is
very close to being saturated for the mineral gypsum
(CaSO ).

37. Punta Laguna Water Chemistry
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The water chemistry of Punta
Laguna is quite different from
Lake Chichancanab. Punta
Laguna is relatively fresh with
total dissolved solids of 835
mg/L.
The dominant anion is
bicarbonate (HCO3).
The lake water is saturated
with respect to calcium
carbonate(CaCO3), which many
aquatic organisms use to form
their shells.

38. Lake Chichancanab Core
Results
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Data from the Lake Chichancanab core supports the
following interpretation that begins at the base of the
core:
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From 9200 to 7800 years BP, there was no lake at the coring site as
indicated by the absence of aquatic microfossils and the presence
of land snails.
Beginning at about 7800 years BP, the lake began to fill but the
salinity was much higher than today.
Evidence for this includes high sulfur content indicating gypsum
precipitation, very high 18O and 16O ratios in both ostracods and
gastropods, and the occurrence of a benthic foraminifera, Ammonia
beccarri.
Foraminiferas are almost exclusively marine forms but this species
can tolerate a wide range of salinity (7 to 67 ppt); however, it only
reproduces between 13 and 40 ppt. The large number of specimens
of A. beccarri suggests salinities of at least 13 ppt (the modern lake
salinity is only 4 ppt).
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39. Lake Chichancanab Core
Results
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The lake basin was filled by 7000 years BP, and relatively wet
conditions prevailed from 7000 to 3000 years BP as evidenced by
low sulfur, high CaCO3, and low 18O and 16O ratios of ostracods and
gastropods.
Beginning about 3000 years BP, a drying trend began that
culminated in peak arid conditions between 1300 and 1100 years
BP.
Evidence for climatic drying includes an increase in gypsum (S)
precipitation and an increase in 18O and 16O ratios. The peak of this
arid event is well dated by an AMS-14C date of a seed taken from the
height of the sulfur and oxygen isotope values.
The radiocarbon date of the seed is 1140 +/-35 years BP, which
translates to a calendar date of 893 A.D.
The collapse of the Classic Maya civilization occurred between 800
and 900 A.D.

40. Data from Lake Chichancanab

41. From Curtis, et al 2007 ©
Oxygen
Isotope
Results
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This slide compares the oxygen isotope record on the same species
of gastropod between the two lake cores: Punta Laguna (above) and
Chichancanab (below).
Note that the Punta Laguna record is much higher resolution owing to
higher sedimentation rates than Chichancanab.
Within the error of the radiocarbon age models, the period of higher
mean 18O values in Punta Laguna correlates with the interval of
increasing sulfur and oxygen isotope values in Chichancanab.

42. From Curtis, et al © 2007
Punta
Laguna
Oxygen
Isotope
Results
The oxygen isotope data measured on ostracods from Punta Laguna
sediments have been converted from radiocarbon years to calendar
years and compared to Mayan cultural periods.
 Superimposed upon the mean changes in the record are distinct
peaks that represent arid climate conditions.
 These peaks occur at 585 A.D., 862 A.D., 986 A.D., 1051 A.D. and
1391 A.D. Error is approximately +/-50 years.

43. Ostracod Climate Data
From Curtis, et al © 2007

44. Comparison of Ostracod Data and
Maya Cultural Periods
From Curtis, et al 2007
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The first peak at 585 A.D. coincides with the early/late Classic boundary.
This boundary is associated with the "Maya Hiatus", which lasted between
530 and 630 A.D.
The Maya Hiatus was marked by a sharp decline in monument carving,
abandonment in some areas and social upheaval.
This event may have been drought-related.

45. Comparison of Ostracod Data
and Maya Cultural Periods
From Curtis, et al 2007
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During the next 200 years from 600 to 800 A.D., the late Classic
Maya flourished and reached their cultural and artistic apex.
The next peak in 18O/16O occurs at 862 A.D. and coincides with
the collapse of Classic Maya civilization between 800 and 900 A.D.
The earliest Postclassic Period was also relatively dry between 986
and 1051 A.D. At about 1000 A.D., mean oxygen isotope values
decrease indicating a return to more humid conditions.

46. Results
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Although a Postclassic
resurgence occurred in
the northern Yucatan,
city-states in the
southern lowlands
remained sparsely
occupied.
These findings
support a rather strong
correlation between
times of drought and
major cultural
discontinuities in
Classic Maya
civilization.
Tikal Temple I and Temple II

47. © Hodell

49. Climate and Oxygen Isotope
Levels
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This illustration shows the simple
working assumptions for interpreting
changes in the sediment record in
terms of climate (evaporation/
precipitation).
Top: Under conditions of wet climate (low
E/P), we expect high lake levels, dilute
concentrations of solutes, low 18O to 16Oratios
in lake water and aquatic shells, and
sediments consisting of mainly organic
carbon and calcite.
Middle: Under conditions of drier climate
(moderate E/P), we expect lower lake levels,
higher concentrations of dissolved solutes,
higher ratios of 18O and 16O, and perhaps
sediments dominated by calcite.
Bottom: Under arid climate conditions (high
E/P), we expect low lake levels (perhaps
desiccation), high dissolved solute
concentrations, high ratios of 18O and 16O
and, in the case of Lake Chichancanab,
sediments dominated by gypsum (CaSO4).