USC Dana and David Dornsife College of Letters, Arts & Sciences

Scientists have discovered a time machine that allows them to analyze records of environmental change to particular land areas subsequent to the duration of Mayan civilization. It’s not an actual device that physically transports them back in time but actually involves the recovery of sediment cores from lakes.

That’s right, the study of accumulated particulate matter helps scientists form a chronology behind the colonization and decline of the Mayan civilization hundreds of years ago. Though the timeline produced from these analyses may not be exact, the evidence proved that the Mayan population significantly impacted the environment they inhabited.

Location and detail of Lake Salpeten

Lake Salpetén, a small closed basin, located in Petén, Guatemala, the southern Maya lowlands, gives scientists access to sedimentation fit for analysis. According to an article entitled, “A 4000-Year Lacustrine Record of Environmental Change in the Southern Maya Lowlands, Pete ́n, Guatemala,” which was written by Michael F. Rosenmeier, David A. Hodell, Mark Brenner, and Jason H. Curtis, the recovery of composite sediment from Lake Salpetén in 2002 provided the first ever high-resolution record of environmental change in the lowlands. I found the human-induced changes to the lake sedimentation to be most interesting.

Certain geochemical variations in the sediment cores reflected the existence of the Mayan population. As the Mayans settled into Lake Salpetén’s area and expanded agriculture through deforestation, there was an increase in soil erosion. In the case of human-induced soil erosion, changes in land use, management and degradation can cause erosion. This movement of soils causes frequent changes in material transfers from the land to the lake as well as in watershed vegetation.

When soil is removed from the land it accumulates in low-lying areas like Lake Salpetén. The displaced soil consists of several different particles representing organic and inorganic matter. Organic matter includes those materials that are essential to soil processes (i.e. wood, seeds and charcoal). Inorganic matter includes particles such as sand, silt and clay. In particular, the presence of corn pollen suggested to researchers that Mayans populated the area because corn crops were important to the Mayan culture.

When there was more organic matter present than inorganic matter within the sedimentation, scientists concluded that there was a less dense population occupying the basin during that time, which was indicative of the fact that there was minimal human activity. On the other hand, when there was more inorganic matter present than organic matter within the sedimentation, scientists inferred that there was a more dense population inhabiting the basin around that time, which suggested to scientists that there was quite a bit of human activity.

Scientists then compared the recovery of these sediments to the already established archaeological prehistory of the region in order to create a chronology of the Mayans’ impact on the surrounding area of Lake Salpetén.

Oxygen isotope data from Rosenmeier et al's survey of the lake.

In addition to the analysis of physical properties within the sediment cores, scientists also considered the change in chemical properties such as the shifts in organic carbon concentrations. Organic carbon is simply any carbon that has come from living organisms such as trees, grass, or leaves. The amount of organic carbon concentration found in the sedimentation correlates to the potential amount of population inhabiting the basin. High amounts of organic carbon concentrations indicated the presence of fewer population numbers while low amounts suggested a boom in the Mayan civilization.

The study found that before the peak height of the Mayan civilization around 1700 B.C., there were high amounts of organic carbon concentrations. This was probably due to the fact that the Mayans were still in their initial stages of settlement. Scientists also took note of low amounts of organic carbon concentrations approximately between 900 B.C. and 850 A.D., which was a time when the Mayan population was reportedly in high numbers. During this particular time period, there was also a boost in human activities such as agriculture expansion and forest clearing, both of which led to the increase of soil erosion and of accumulated sedimentation in Lake Salpeten.

However, sometime around 850 A.D. marked the beginning of the fall of the Mayan civilization. As proof of this factor, the amount of organic carbon concentrations suddenly increased.  The reduction in anthropogenic activities and decline in Mayan population allowed the recovery of forests and stabilization of soils, which in turn, allowed for more organic carbon concentrations to gather in the sediment.

In relation to more recent years, evidence from the sediment cores implied a decrease in organic carbon concentrations. This finding correlates to the repopulation of the Mayans in the last 300 years. Thus, the commencement of agriculture expansion and deforestation as well as the influx of inorganic matter are in place yet again.

The ability of scientists to track the history of the Mayan civilization through analyzing composite sediment profiles is impressive. It not only demonstrates the power of today’s technology and intelligence but also of the earth’s capacity to preserve its own history. Though the study of sediment accumulation in Lake Salpetén was considerably successful, it is only because the conditions of this lake provided fairly pristine material. It would be difficult to perform such an examination on composite sediment taken from lakes in the United States, for example. This is because the bodies of water like the Great Lakes and the Mississippi river are not as well preserved as Lake Salpetén and are constantly disturbed by human activity and urbanization.

Source:

Rosenmeier, Michael F et al. “A 4000-Year Lacustrine Record of Environmental Change in the Southern Maya Lowlands, Petén, Guatemala.” Quaternary Research 57.2 (2002): 183-190.

Ticia Lee is a sophomore majoring in Public Relations and minoring in Environmental Studies. Upon graduation, she hopes to work for a company that effectively communicates environmental awareness to the general public. Being a city girl from San Francisco, Ticia enjoys spending time in the great outdoors as much as she can. This is her second time participating in one of USC Dornsife’s Problems Without Passport programs.