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A Summary of the Olorgesailie Drilling Project

September 2 to October 4, 2012

and the

Olorgesailie Core Workshop

April 22 to May 2, 2013

Dr. Rick Potts, Human Origins Program National Museum of Natural History, Smithsonian Institution

July 2013

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Twenty-two researchers from around the world participated in the Olorgesailie core

workshop from April 22 to May 2, 2013. The team collected samples every 48

centimeters in order to carry out many different kinds of environmental analysis.

Sediments obtained by drilling totaled 216 meters.

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Introduction

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 region where the evolution of our species is

considered to have occurred.

This report summarizes the initial results of the workshop and future

implications for the study of human evolution. It also offers photographic

documentation of the scientific rationale and the activities of the workshop.

The workshop and the first year of analysis of the core have been funded by the

William H. Donner Foundation, New York; the Ruth and Vernon Taylor

Foundation, Montana; a gift from Whitney and Betty MacMillan; and the Peter

Buck Fund for Human Origins Research.

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Background

The Olorgesailie Drilling Project is the first to successfully obtain a long

sediment core from an early human fossil site. From September 2 to October 4,

2012, the effort to recover the core was successfully carried out in collaboration

with Kenyan partners, including the National Museums of Kenya and the

Oldoinyo Nyokie Group Ranch. The core, lifted from two boreholes in

segments 3-meters long, represents a detailed record of lake sedimentation.

Obtaining the core involved the use of heavy drilling machinery under the

direction of Drilling and Prospecting International (Nairobi, Kenya). The

operation recovered sediments layered since prehistoric time up to 162 meters

below the surface, reaching the volcanic floor of the Rift Valley.

Through previous research at the site, Potts’ team has discovered that

fundamental changes in the behavior of our early human ancestors took place

near and around this site. However, due to erosion, much of the environmental

history that might have influenced many of these changes has remained

unknown. The Olorgesailie Drilling Project endeavored to find a way around

this problem. The site where the drilling took place was chosen after two

decades of geological studies that pointed to the presence of a lake that has now

vanished yet recorded in sediments buried deep underneath the surface.

Retrieval and field inspection of the lengthy core, drilled from two locations,

validated the presence of the suspected lake. Since lake sediments typically

preserve environmental evidence in great detail, analysis of the core is thought

very likely to provide an unprecedented look at the composition of the

environment across time in the South Kenya Rift Valley.

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The Workshop and Its Results

Scientists from research institutions in the U.S., Canada, Kenya, China,

Germany, and Belgium gathered in Minneapolis in April 2013. The team was

selected by Potts after extensive discussions with colleagues and an assessment

of publications and research productivity. 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 with Potts about how to sample

across the continuous layers of sediment.

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.

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

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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.

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 40

Ar/39

Ar 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.

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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

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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 on the next page outlines the overall direction of the

Olorgesailie drill core research.

Support from the William H. Donner Foundation (New York); the Ruth and

Vernon Taylor Foundation (Montana); Whitney and Betty MacMillan; and the

Peter Buck Fund for Human Origins Research (Smithsonian) has been

indispensable in funding the workshop and the range of analyses planned for

2013 through early 2014.

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Collaborations

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

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. We also acknowledge with thanks the South Rift

Association of Landowners (SORALO), particularly Mr. John Kamanga, for

facilitating communications with the landowners and group ranch where the

drilling was carried out.

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.

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The Kenyan Olorgesailie research 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.

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Direction of scientific study in the Olorgesailie Drilling Project. The first step is to

develop approximately 30 distinct indicators of ancient environment and geological age;

this research is planned to take 18 months. A workshop planned for November 2014

will be devoted to integrating the environmental sequences into a time-series analysis of

environmental dynamics, which is essential for modeling habitat dynamics, resource

abundances, and environmental uncertainties. It is on this basis that processes of

evolution – natural selection, speciation, and extinction – will be modeled. The flow of

work thus connects the acquisition of the drill core, sampling of the core, and critical

tests concerning the evolution of humans and associated organisms.

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The northern Olorgesailie basin (above) is deeply eroded, which affords an opportunity

to excavate fossils, artifacts, and environmental evidence between 1.2 million and

500,000 years old. The north was uplifted due to earthquakes around 500,000 years ago,

leading to a less complete record beginning at that time. At that critical point, the main

lake shifted southward.

This southern area (see below) is flat and was never uplifted by earthquakes. The

drilling activity obtained a continuous, high-precision record of environments for the

past 500,000 years from the south.

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The Olorgesailie Drilling Project

collected 189 meters of sediments in

139 core segments, and also 27

meters of sediments in bags (1 meter

per bag) from the drill holes.

Each cylinder of core (4 centimeters

diameter) had to be split by a

specialized band saw, as done here

by Anders Noren, the head of the

National Lacustrine Core Facility,

where the workshop took place.

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, as Peter

deMenocal, Rick Potts, Stephen

Rucina, and Alan Deino are doing

(below).

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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.

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As the core was studied, microscopic analysis showed an abundance of fossil diatoms

and pollen, plant phytoliths, and various other forms of lake organisms that will help

reconstruct environments through time. The core also had abundant bits of charcoal,

indicating the potential impact of early humans on the landscape surrounding the lake.

René Dommain and Bernie Owen are shown here conducting smear slide analysis.

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A short portion of the Olorgesailie lake core, split open to reveal

layers of environmental fluctuation in the East African Rift Valley

of southern Kenya. The scale on the left is in centimeters. The thin

bands preserve an annual record of rainfall, vegetation, and other

weather variables. Each layer was formed as microscopic organisms

called diatoms alternated with clay and volcanic ash. This ancient

deep lake is the ideal place for preserving a high-precision record of

climate during the time when Homo sapiens evolved.

More than 150 volcanic ash layers are preserved in 189 meters of

core obtained by the Olorgesailie Drilling Project. These layers, like

the dark one shown above, can be dated by precise argon dating.

The sharp contact between a dark soil and banded lake deposits

(below) illustrates a sharp rise in lake level – one of many abrupt

shifts in climate and landscape evident in the Olorgesailie core.

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This first analysis of the Olorgesailie core illustrates likely climate cycles in the lower

portion (120-162 meters) of the long core, ODP-1A. Peaks in magnetic susceptibility

(red curve) suggest ~20,000-year wet-dry cycles governed by orbital precession (related

to the wobble in Earth’s axis of rotation). These cycles appear to occur every 4-to-6

meters of this section of the core. Graph courtesy of Peter deMenocal.

meters below the surface

Gamma radiation

Magnetic susceptibility

Magnetic susceptibility & Gamma radiation analysis Core 1A: 120 – 166m

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Olorgesailie Drilling Project Core Sampling – Participants & 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 δ13

C (vegetation);

δ18

O, 17

O, 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 (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

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The workshop team on the steps of the National Lacustrine Core Facility, University of

Minnesota, Minneapolis, where the Olorgesailie core is permanently archived.