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Olorgesailie Drilling Project

The Olorgesailie Drill rig on a grassland surrounded by acacia trees with Mt. Olorgesailie in the distance
The Olorgesailie Drilling Project, with Mt. Olorgesailie in the distance


First Steps To the Drilling Project

The National Research Council of the U.S. National Academy of Sciences issued a report on March 3, 2010, titled ‘Understanding Climate’s Influence on Human Evolution’.

One of the report’s chief recommendations is to build a new scientific program for drilling ancient lake sediments in eastern Africa and other regions in order to obtain long climate records in the areas once inhabited by early hominins. This approach would be coupled with new lake and ocean drilling in order to understand worldwide, regional, and local climate dynamics relevant to the time periods and the regions where human evolutionary change took place.

Strategically-placed drill cores will capture the continuous, fine structure of the environmental record, which is vitally important in studying questions about changes in Earth’s climate, environment, and geological forces. The cores will allow sufficiently high resolution to study short-duration events and processes (e.g., seasonality, interannual change, volcanic episodes, tectonic events) and to see how these relate to environmental changes over evolutionary time scales that may have influenced the evolution of human adaptations.

The Smithsonian’s Human Origins Program is helping to lead this international effort to explore the parallels and connections between environmental change and human origins. Over the months to come, follow here the development of this new approach to studying human evolution.

Read the NRC report on the National Academy of Science's website.


A wire services report by ClimateWire summarized the NRC report in the following way:

Research on climate change today focuses mostly on the future, taking stock of how humans have influenced the planet and using computer models to project unwanted changes like warming temperatures or rising seas and ways we might avoid them.

But a new report suggests that there's value in looking at not just how humans shape the climate, but how the climate shaped human development going back millions of years.

"How we get here is relevant to where we are going as a species," says the analysis released yesterday by the National Academy of Sciences. Written at the behest of the National Science Foundation, it lays out a 10- to 20-year plan for research that would improve understanding of the ancient climate and how that influenced human evolution.

Rick Potts, a Smithsonian Institution paleoanthropologist who helped write the report, said that until about 20 years ago, scientists had a simplistic view of how the environment shaped human history. They believed that a few major events, like the expansion of grasslands in Africa and later ice ages in Europe and Asia, signaled forks in the evolutionary path that led to Homo sapiens.

But with more data available now on ancient climate -- such as temperature records derived from sediment cores drilled from lake beds and ocean floors -- researchers now believe humans evolved amid "a great deal of instability and environmental fluctuation," said Potts, director of the Human Origins Program and curator of anthropology at the National Museum of Natural History.

"The human species today is a survivor of lots of different environmental changes," he said. "The possible implication is that we have, built into us, a certain degree of adaptability or resilience."

But history also shows there are limits.

"Look back to the fossil known as 'Lucy' -- her species, Australopithecus afarensis, lived back beyond 3 million years ago," Potts said. "Her species had a certain resilience to environmental change, but her species is no longer around."

A more recent example is the Classic Mayan civilization in southern Mexico and Central America, the report notes. Over a 400-year span between 750 and 1150, the Mayan population dropped by 70 percent or more.

'We're in an experiment that's never been tried' 

Some archaeologists believe that a series of protracted droughts helped bring about the Mayans' downfall, basing their controversial theory on climate information gleaned from sediment cores.

Potts said he believes the research program outlined in the new report would help society look to its future, not just better understand its past.

The science academy panel is recommending an effort to broaden the collection of fossils to new geographic areas and across time periods, expand scientific drilling programs in lakes and oceans near sites where ancient humans evolved, and improve climate models to help scientists reconstruct the environment of the past.

That could help researchers understand how fast the environment changed at different points in human history -- and how that compares to conditions today.

"I think we need to look very closely at climate changes in the past and compare them to climate changes in the present and see where our sources of resilience will come from," Potts said. "What we're in now is an experiment that has never been tried. Homo erectus was never able to modify the landscape in the ways we do today."

"There's kind of a cautionary message there," he said, "but also a hopeful one."

 ClimateWire, A Proposal to Search the Past for Adaptation Clues, Lauren Morello, E&E reporter, March 4, 2010


Potts's American and Kenyan team of drillers and core-recovery experts undertook day- and night-time drilling
Potts’s American and Kenyan team of drillers and core-recovery experts undertook day / night-time drilling. This approach to doing human origins research had not previously been tried. It has now led to a new way of conducting studies into human evolution



October 2012 - Drilling the Core


The Smithsonian’s Human Origins Program team, led by Dr. Rick Potts in collaboration with the National Museums of Kenya, has obtained the first long climate core from an early human fossil site.  The purpose in recovering the core is to investigate in greater detail than ever before the environments connected with the origin of our species in Africa, along with the events leading up to this benchmark in the history of life. 

The goal was to obtain this climate core by drilling at the prehistoric site of Olorgesailie, located in the southern Kenya Rift Valley.  Potts’s previous excavations there have documented fundamental changes in the behavior of our early human ancestors over the past 500,000 years.  However, many tens of thousands of years of this period are missing due to the erosion of sediment layers visible above ground in the Olorgesailie region. The reason for drilling was to recover sediment layers underground that preserve a complete, high-precision record of rainfall, temperature, vegetation, and environmental stresses – and how these changed over time – during the critical transitions involved in the origin and evolution of Homo sapiens.

The drilling focused on a flat, grassy plain in the previously unexplored southern region of the Olorgesailie basin.  Two decades of geological studies led our team to think that if the past 500,000 to 600,000 years of ancient lake deposits existed in the southern Kenya Rift Valley, they would occur under the flat plain where the layers could be accessed only by drilling.


Collaborations with the following partners were vital to the success of this project:


Drilling and Prospecting International, Ltd. (Kenya)  DPI was responsible for carrying out the core drilling operation. Very special thanks to Mike Scarpellini, Natascha Sole and the rest of the DPI crew members.

Earthview Geoconsultants Ltd. (Kenya)  Special thanks to Dr. Dan Olago and his team for the environmental impact study in the vicinity of the drilling site before, during, and after the project.

Oldoinyo Nyokie Group Ranch (Kenya) The Maasai landholders in the drilling area belong to a group ranch headed by Mr. Joseph Sakaya. The Olorgesailie project has enjoyed the support and friendship of the group ranch families and leaders. Several members of the community were employed by the project; they learned various aspects of the drilling work and core processing, and contributed to the safety of our field camps. These individuals included:  Eliud Pussaren, Moses Saitoti, Keliya Lemparakwo, Taota, Jackson Keliya, Kishanto Kipampa, Tenge Ntinana, and Melita Samare.  Electrical generators and other useful supplies were donated to the Nyokie community at the conclusion of the project.  

The Olorgesailie Kenyan team:  Under the leadership of Muteti Nume, our crew foreman, the following individuals contributed to our field camp and efforts during the drilling operation – Musyoka Kilonzi, Vincent Kimeu, George Mumo, Muthengi Kioko, Sina Muteti, King’ola Ndambuki, Mutuku King’oo, Nzioki Mativo, Kamula Kawaya, Kakai ole Mindo, Tima ole Kikanai, Bernard Mukilya, Katui Kasivo, Peter Asumani, Sila Nzivo, and Muthiani Makuu.

Drilling, Observation, and Sampling of Earth’s Continental Crust (DOSECC)  and DOSECC Exploration Services (DES) (USA)  DOSECC and DES advised the project on scientific drilling techniques, provided specialized coring equipment and shipped supplies for the project. With special thanks to Beau Marshall and Joe Bolin for their on-site supervision and coordination with DPI’s drilling crew.

University of Minnesota’s LacCore:  National Lacustrine Core Facility (USA). Special thanks to Anders Noren, Kristina Brady, and René Dommain for processing and recording the cores on-site, training local assistants from the Oldoinyo Nyokie community, and preparing the cores for shipment to LacCore’s facility for scientific study and archival storage.



From September 2 to October 4, 2012, the effort to recover the core was successfully carried out.  The core, lifted from two boreholes in segments 3-meters long, represents a detailed record of lake sedimentation.  Through the plastic liners in which the core was recovered, fine laminations of diatomite and clay lake deposits can be seen, along with inputs of fine silts and sands – all of which we believe capture the environmental dynamics of this region of the East African Rift Valley over approximately the past 500,000 years.


Two men wearing hard hat and safety vest pulling a long thin plastic tube of cored sediment from a metal casing
A 3-meter-long core is extracted in its plastic liner from the core barrel, which was brought up from the 30- to 33-meter level below ground.



close up view of a clear plastic tube containing banded layers of sediment core
The laminations visible through the drill core liner suggest that even changes in the annual seasons of rainfall and vegetation are preserved in this core.



The cores extend down to 166m below the ground surface, and provide evidence of the ancient lake that had not previously been visible but that we suspected must have existed in the drilling area.  

Unexpected challenges in recovering these cores occurred, but all were solved so that the project started and was completed on time. These challenges included initial difficulties in getting drilling rods, core liners, and other critical supplies into Kenya, a rupture in the water pipeline in the closest town of Magadi, which was to supply the drilling water at no cost to the project, and damage to the drilling rods during the first several days of drilling due to our team’s unfamiliarity with the specialized rods sent from the U.S. for this project. Project funding along with the expertise assembled at the drill site were instrumental in meeting and solving these challenges as they arose.


Future Study and Implications

The Olorgesailie team is excited about the results of the core drilling.  Knowledge gained from our two decades of study elsewhere in the Olorgesailie region imply that the layers of lake sediment in the cores represent the past 500,000 years in high-resolution.  We will employ direct methods of dating the volcanic tephra in the core.  If our current understanding of the age range is correct, the core will give us the most exact record of climatic stresses and ecological change in East Africa during four key chapters in human evolution: 

  1. The earliest transition from handaxe technology to innovative technologies, including projectiles (i.e., being able to hunt at a distance); this transition is recorded at Olorgesailie between 500,000 and 300,000 years ago;
  2. The origin of the modern East African biota, which occurred in the same era;
  3. The origin of our species, around 200,000 years ago; 
  4. An era of low population size or population crash in Homo sapiens in Africa 100,000 to 70,000 years ago, just prior to the global expansion of our species.

Investigating the environmental challenges of these eras will allow us to test and determine as best as possible how evolutionary processes of survival helped shape the human species. 

The first of two steps in this project have been completed.  The ultimate goal is not only to recover the cores but to produce well-studied cores, which we believe will yield benchmark scientific papers in the study of human origins.  In late April 2013, Potts will assemble an international team of 20 to 25 scientists to open the cores, which will be housed at the international lake core facility, LacCore, at the University of Minnesota, Minneapolis.  At the week-long workshop, our scientific team will describe and sample the cores for detailed analysis, followed by 12-24 months of laboratory studies, project workshops, synthesis of results, and the writing of publications.


Support from the William H. Donner Foundation (New York); the Ruth and Vernon Taylor Foundation (Montana); and the Peter Buck Fund for Human Origins Research (Smithsonian) has been indispensable in enabling us to achieve the first step in this project.  Projects are also being planned by other research teams to try to recover ancient lake cores from other famous fossil sites in East Africa.


Four scientists crowd around a lab bench collecting samples from geological cores in long tubular trays.
Twenty-two researchers from around the world participated in the Olorgesailie core workshop. The team collected samples every 48 centimeters in order to carry out many different kinds of environmental analysis.


April 2013 – Olorgesailie Drill Core Workshop I


From April 22 to May 2, 2013, twenty-two scientists and drill core experts participated in the first Olorgesailie Drilling Project workshop, organized by the Smithsonian’s Human Origins Program under Dr. Rick Potts’s leadership. The workshop was held at the National Lacustrine Core Facility (LacCore, University of Minnesota, Minneapolis), where the Olorgesailie drill core is permanently housed. The workshop’s objective was to bring together a world-class scientific team to begin sampling the core for analysis, an effort that will include thirty distinct measures of climate dynamics, vegetation, and geological age. These measurements are expected to provide the first continuous, high-precision record of climate change and environmental dynamics in Africa covering the past 500,000 years.

Due to its location in the East African Rift Valley, study of the core aims to examine in exceptional detail the conditions leading up to and following the origin of Homo sapiens in the general region where the evolution of our species is considered to have occurred.

Workshop and Results

Scientists from research institutions in the U.S., Canada, Kenya, China, Germany, and Belgium gathered in Minneapolis in April 2013.  Day 1 was devoted to introductions and presentations by Potts about the scientific background and goals of the Olorgesailie Drilling Project, and by Dr. Kay Behrensmeyer (Smithsonian) about the geological history of the Olorgesailie region. Anders Noren, Director of LacCore, also introduced the laboratory procedures involved in opening and sampling the core, based on prior discussions about how to sample across the continuous layers of sediment.


Four scientists stand near a lab bench to examine a core split in two halves.
An example of a core segment split in half, allowing detailed study and much discussion by the scientific team, including Anders Noren (top), Kay Behrensmeyer, Bernie Owen, Rick Potts, and Liz Pennisi.


 A total of 216 meters of sediment recovered from two drilling locations were studied by the workshop participants. Detailed sampling at 48 centimeter intervals was focused on 162 meters of deposits recovered from the first drilling location (Core 1A). Segments of the core typically ranged between 1 and 3 meters long, and each segment in its original plastic liner was sawed in half using specialized band saws in order to allow inspection of the sediment layers and analytical sampling.


Anders Noren wearing a white lab coat, eye and ear protection, stands beside a band saw as it splits a core tube in half
Each cylinder of core had to be split by a specialized band saw, as done here by Anders Noren, the head of the National Lacustrine Core Facility


Peter deMenocal, Rick Potts, Stephen Rucina, and Alan Deino comparing a core to its digital image
The workshop gathered experts in paleoclimate, geological dating, fossil pollen, isotope chemistry, and several other areas of study. Each core was compared to high resolution images by Peter deMenocal, Rick Potts, Stephen Rucina, and Alan Deino.


Splitting of each core segment revealed finely-laminated layers of clay and silt typical of sediments that build up in lakes. The layer-by-layer composition of each core segment was described in detail. At major shifts in sediment type, small sediment samples were taken and placed on slides for microscopic analysis; this smear slide analysis demonstrated the presence of fossil diatoms, pollen, phytoliths, charcoal, and other microfossils. Fine laminations through much of the core are likely to provide an annual record of rainfall, temperature, fire, and vegetation, as well as seasonal shifts in these variables. Disruptions in the sedimentary beds were also observed as wavy contacts between the layers, indicative of earthquake activity. Careful study of these disruptions can provide data on the frequency of faulting and its effect on regional environment.


 René Dommain and Bernie Owen sitting side-by-side at a lab bench looking into microscopes.
René Dommain and Bernie Owen examine samples under the microscope. Samples showed an abundance of fossil diatoms and pollen, plant phytoliths, and various other forms of lake organisms that will help reconstruct environments through time.


Image of Olorgesailie Core with identifying text


During the workshop, the team collected a total of 2,461 sediment samples for a wide variety of specialized analyses. The types of samples included:

  • U-channels: continuous u-shaped samples extracted from the middle of every core segment; these samples will enable study of rock magnetics and environmental indicators, which can be compared against worldwide data on magnetic variability and African records of environmental change.
  • Volcanic ash and pumice:  Samples were collected from more than 150 layers in order to carry out precise age determinations using the single-crystal 40Ar/39Ar method; analysis of these samples is likely to provide exceptional age control for the Olorgesailie core.
  • Multiple samples (1 to 5 mg each) were obtained every 48 centimeters for the purpose of careful analysis of pollen, phytoliths, fungal spores, plant biomarkers, charcoal, ostracods, diatoms, isotope chemistry, clay minerals, and variety of geochemical indicators of the spectrum from intense aridity to extreme precipitation.


Future Study and Implications

The 2013 workshop was the first step in the comprehensive study, documentation, and publication of the Olorgesailie drill core. Our team expects this work to yield landmark papers that will contribute and stimulate major developments in the field of human origins research.  Because of the vast temporal span of environmental information represented in the sediment samples obtained from the Olorgesailie core, major changes on the timeline of human evolution will likely be contextualized or even explained by environmental challenges and stresses following more thorough research.  Some of these prehistoric milestones recorded at Olorgesailie or in the surrounding area of East Africa include the development of innovative technologies like projectile weapons, the origin of modern East African wildlife, the origin of the human species, and the factors responsible for the small population size in Homo sapiens followed by the global spread of our species from Africa beginning 60,000 years ago.

Among the many exciting results of the workshop was the potential to employ direct analyses of volcanic deposits in order to date the core. Although we knew that Olorgesailie is located in an area of past volcanic activity, the number of separate volcanic eruptions represented in the core is extraordinary. If our current understanding of the age range is correct, the core will give us the most exact record of climatic stresses and ecological change in East Africa leading up to crucial evolutionary changes pertinent to the origin of our species.

The workshop afforded the opportunity for the scientific team to build a strong common purpose, motivation, and schedule. The research participants have agreed to a period of 18 months for analysis and the development of the datasets necessary to understand climate change and environmental dynamics in fine detail, which will be brought together in a workshop planned for November 2014.  The figure  below outlines the overall direction of the Olorgesailie drill core research.


Diagram of direction of scientific study in the Olorgesailie Drilling Project.


Support from the William H. Donner Foundation (New York); the Ruth and Vernon Taylor Foundation (Montana); the Peter Buck Fund for Human Origins Research (Smithsonian); and Betty and Whitney MacMillan has been indispensable in funding the workshop and the range of analyses planned for 2013 through early 2014.


Photo of the Olorgesailie Drill Core Workshop participants standing on the steps of the LaCore Facility building, University of Minnesota.
Group photo of the Olorgesailie Drill Core Workshop participants, LaCore Facility, University of Minnesota.


Olorgesailie Drilling Project Core Sampling – Participants & Scientific Analyses

Rick Potts (Smithsonian): project leader; paleoanthropological analysis

Kay Behrensmeyer (Smithsonian): sediment description, geological correlation

Alan Deino (Berkeley Geochronology Center): Ar-Ar analysis (core dating)

Bernie Owen (Hong Kong University): diatom analysis; sediment description

Robin Renaut (U. Saskatchewan): geochemical analyses, seismites study

Naomi Levin (Johns Hopkins U.): carbonate δ13C (vegetation); δ18O, 17O, D47 (temperature)

Rahab Kinyanjui (National Museums of Kenya): fossil phytolith analysis

Stephen Rucina (National Museums of Kenya):  fossil pollen analysis

Vanessa Gelorini (U. Ghent, Belgium): fossil fungal spores

René Dommain (U. Greifswald, Germany): smear slide & grain size analysis

John King (U. Rhode Island): rock & environmental magnetics

Danielle Cares (U. Rhode Island): U-channel sampling

Erik Brown (U. Minnesota, Duluth): Scanning XRF, digital X-radiography

Peter deMenocal (Lamont, Columbia U.):  leaf wax biomarkers (vegetation)

Kevin Uno (Lamont, Columbia U.): leaf wax biomarkers (vegetation

Jim Russell (Brown U.):  %TOC, TN, TIC; organic C, N isotopes; leaf wax biomarkers (temperature)

Dan Deocampo (Georgia State):  bulk XRD, clay mineralogy & geochemistry

Andy Cohen (U. Arizona):  fossil ostracods, charcoal abundance

Jordan Bright (U. Arizona):  ostracod microfossil analysis

Anders Noren (LacCore):  workshop organizer; core sample manager

Kristina Brady (LacCore):  Olorgesailie core curation

Ryan O’Grady (LacCore):  core sampling technical support

Jennifer Clark (Smithsonian):  workshop logistics; photo image curator

Elizabeth Pennisi (Science magazine): science reporter


November 2014 - Olorgesailie Drilling Project Workshop II


During the second workshop, the research team presented their initial analytical results obtained by working on samples collected during the first workshop 18 months earlier. Scientists from the U.S., Canada, Kenya, Germany, Switzerland, Hong Kong, and Australia convened November 14th – 16th, 2014, at the Smithsonian’s National Museum of Natural History in Washington, DC.


View of room full of participants sitting at tables with laptops watching a presentation by Rene Dommain.

The presentations included:

  • Paleoanthropological and geological background (Rick Potts)
  • Detailed lithological composition, stratigraphy, and visual images of the core (Kay Behrensmeyer, René Dommain)
  • Argon-argon dating (Alan Deino)
  • Scanning XRF and elemental composition through the core (Mona Stockehecke, Erik Brown)
  • Magnetics (John King)
  • Grain size and magnetic susceptibility (René Dommain)
  • Structural geology of the southern Kenya Rift (Robin Renaut)
  • Geochemistry (Dan Deocampo, Nate Rabideaux)
  • Organic materials and stable isotopes (Kevin Uno, Naomi Levin, Jim Russell, René Dommain)
  • Diatoms (Bernie Owen, Veronica Muiriru), ostracods and other lake microorganisms (Jordan Bright, Andy Cohen), phytoliths (Rahab Kinyanjui), pollen (Stephen Rucina)
  • Core-to-outcrop correlations (Kay Behrensmeyer, Alan Deino)
  • Hominin and faunal evolutionary benchmarks and climate variability (Rick Potts)
  • Modeling and statistical treatments of the data (John Kutzbach, Peter deMenocal, Tyler Faith)
  • Participants also included Kristina Brady (LacCore) and Alison Brooks, Jennifer Clark, Catherine Denial, and Anna Ragni (Smithsonian’s Human Origins Program)



Workshop participants examining large monitors display of detailed photograph of a cross section of a sediment core
Andy Cohen, Kay Behrensmeyer, Nate Rabideaux, Erik Brown, Kevin Uno, and Naomi Levin compare images of the core sediments to measures of magnetic susceptibility.

Some of the highlights included Al Deino’s single crystal Ar/Ar dating analyses, which demonstrate the that the main core (Core 1A, 166m deep) provides an extraordinary chronology from near the present (surface) to 500,000 years ago (140 meters below surface), and back to nearly 700,000 years ago (155 meters below surface), lying on top of volcanic rock more than 1 million years old. This preliminary chronology will enable all of the data sets to examine changes in the ancient lake, landscape, and climate through time.

The core also preserves its finest detail, including potentially seasonal changes in weather and vegetation, at the time of the oldest known Middle Stone Age and major faunal changes, which are evident in excavations within the Olorgesailie Basin.

There were surprises, too, such as evidence of a deep lake in the drilling sites on the Koora Plain during a period of deep erosion in the northern Olorgesailie Basin. Understanding the sedimentary relationship between the Koora and Olorgesailie areas of the basin, and possibly the development of two sometimes independent basin histories, provides an exciting challenge in our future work.

Discussions in small groups allowed the team to examine the core images in detail, classify sediment types, and discuss problems in interpreting the core.


Naomi Levin plotting data on a large printout of core diagram posted on a wall
Naomi Levin and Catherine Denial plot the distribution of different sediment types through the main core (Core 1A)


The research group had extensive discussions about links between the data sets, including some preliminary statistical treatments, and what they might signify about the conditions of the ancient lake, terrestrial dynamics, and local climate at different intervals of the core. The potential is very high in linking detailed climate dynamics with significant events in human evolution, as represented at Olorgesailie. The workshop concluded with plans for future research, including concentrated analysis of particular intervals.


Group photo of 24 workshop participants
The scientific team convened at the ODP Second Workshop


November 2015 - Olorgesailie Drilling Project Workshop III


Deep sediment cores were recovered by drilling in the Koora area south of Olorgesailie, Kenya, in a project under Rick Potts’s direction in 2012. The total of 216 meters of sediment, reaching the bottom of the Rift Valley in two locations, continues to be studied by an international team of 32 scientists and PhD students. In November 2015, a second workshop devoted to detailed sampling of the core was held at the National Lacustrine Core Facility (LacCore) in Minneapolis, MN, where the cores are conserved. A dozen researchers participated for a week of laboratory work, presentations, and discussions. The additional sampling will help develop what will be the most precise record of changing climates anywhere in the world for the past half million years. Publications are planned for late 2016 detailing the dating and indicators of climate variability as the context for the evolutionary origin of Homo sapiens.  The photos below offer a look at the laboratory activities during the workshop.

close-up image of sediment sample showing banding of grey, brown and cream colored sediment layers
Detail of drill core 1A. The thin lines of sediment represent rainy and dry seasons. The core offers the first opportunity to examine such fine resolution of climate variability from a critical period in evolution just prior to the origin of our species.


Image of three scientist scooping sediment samples from a tray holding one half of a drill core section
Jessica Moerman, Eric Brown, and Rick Potts collect samples for isotopic, geochemical, and biological assays, which will help identify the environmental conditions of East Africa during a key transition in early human technology and animal communities.


Three scientist looking at computer monitors displaying enlarged image of a drill core section
Kay Behrensmeyer, Emily Beverly, and Jenni Scott examine high-resolution images of the drill core to locate evidence of burrowing invertebrates and soil formation, which reflect times of low lake level and drought in the past.


During July fieldwork in Kenya, Rick Potts organized a field workshop of geologists from the U.S., Kenya, Germany, Canada, China, and Argentina. The workshop conducted the first survey of three adjacent sedimentary basins in the South Rift. The purpose of this effort was to develop hypotheses about the lake history in this region and how early human populations responded to lake dynamics and the availability of water over the past 500,000 years.

The existence of a large lake in the Koora region had previously been documented by the Olorgesailie Drilling Project. The 2015 workshop found that over the past 500,000 years water has flowed into Lake Magadi from the Koora area. The workshop team investigated a deep gorge that connects the two areas, Koora and Magadi, creating a conduit for water to pass from Koora during times of high lake level into the Magadi basin. The geological team also discovered shorelines of previous lake levels in Koora. These findings initiated a more detailed study of Koora’s interesting environmental history and its relevance to how and when early human populations moved in and out of the South Kenya Rift.

map showing largest extent of Lake Koora, Kenya in the past

Dr. René Dommain, a Postdoctoral Fellow supported by the Peter Buck Fund for Human Origins Research, led a new effort to study the southernmost reaches of the Koora area. His work seeks to understand the most recent history of the lake and landscapes in the South Kenya Rift Valley. The researchers discovered deposits of white lake sediments between 2 and 7 meters thick along the western and southeastern margins of the Koora area. These sediments are made up of diatoms, tiny algae that live in lake water, construct microscopic skeletons that reflect the chemistry of their surroundings, and then accumulate after they die as thin layers on the lake floor. The thickness of the sediments testifies that the ancient lake existed for several thousand years. The lake sediments also contain numerous layers of shells of snails and mussels, which lived in the shallower waters of the ancient lake. The shells of these animals can be used to determine the age of the sediments by radiocarbon dating. According to initial results, these lake sediments represent the earliest known evidence of an intense rainy period in Africa around 15,000 years ago. We will determine the age of 18 more samples to better understand the duration of the lake episode. René’s research team collected samples 10 centimeters apart in order to conduct microscopic and chemical analyses that reflect the size and chemistry of the lake that used to exist in the area.

Page last updated: September 14, 2018