Olorgesailie Pre-Historic Site

Olorgesailie Pre-Historic Site is a world-renowned archaeological and paleontological treasure located in the Great Rift Valley in southern Kenya. Widely celebrated as the “factory of stone tools,” it boasts the largest concentration of Acheulean handaxes anywhere in the world, left largely undisturbed in their original context (in situ).

Set against the dramatic backdrop of two extinct volcanoes, Mt. Olorgesailie and Mt. Oldonyo Esakut, the site preserves over a million years of human evolutionary history. It provides unparalleled evidence of the habits, environment, and cognitive development of early human species, particularly Homo erectus, spanning from 1.2 million to 400,000 years ago.

First discovered by British geologist J.W. Gregory in 1919, the site was famously excavated in the 1940s by legendary archaeologists Louis and Mary Leakey, and later by Glynn Isaac and a Smithsonian-led team.

Today, managed by the National Museums of Kenya and recognized on the UNESCO World Heritage Tentative List for its Outstanding Universal Value, Olorgesailie offers visitors a profound journey back in time to the actual camping and butchering grounds of our ancient ancestors.

Location & Accessibility

Olorgesailie is located in Kajiado County, deep within the semi-arid floor of the Great Rift Valley. Its proximity to the capital makes it an ideal and accessible day-trip destination or a fascinating stopover for travelers en route to Lake Magadi.

By Road:

✓ Travel Time: 1.5 to 2 hours, depending on Nairobi city traffic.

✓ Distance: Approximately 70 to 90 km (43 to 55 miles) southwest of Nairobi.

✓ Vehicle Requirements: The main Magadi Road is tarmacked, but a vehicle with decent ground clearance (such as an SUV or 4×4) is recommended for the final unpaved stretch and for comfortably navigating the rugged Rift Valley terrain.

✓ Final Stretch: About 40 km north of Lake Magadi, look for the prominent National Museums of Kenya signboard on the left side of Magadi Road. From this turnoff, a short 1.5 km dirt road leads directly to the site museum and headquarters.

✓ Route: The journey begins by driving from Nairobi through Lang’ata and Kiserian, before continuing onto Magadi Road. The route descends the dramatic Rift Valley escarpment, offering sweeping, panoramic views of the valley floor and the Ngong Hills—before entering the dry, acacia-dotted plains.

By Air:

✓ Primary Hubs: Most visitors access the region by flying into Nairobi’s Jomo Kenyatta International Airport (JKIA) or Wilson Airport, followed by a scenic road transfer down into the Rift Valley.

✓ Nearby Airstrips: Light charter aircraft can also fly into the Magadi Airstrip, located further south at Lake Magadi. From there, visitors can arrange a 40 km road transfer north to explore the prehistoric site.

✓ Helicopter Charters: For an exclusive and time-efficient arrival, private helicopter charters can be arranged from Nairobi (Wilson Airport). A helicopter flight offers breathtaking aerial perspectives of the Great Rift Valley, the Ngong Hills, and the extinct Mt. Olorgesailie volcano before landing near the site.

Olorgesailie is globally celebrated as the “factory of stone tools.” It holds the distinction of having the highest concentration of Acheulean handaxes preserved in situ (in their original place) of any archaeological site in the world.

✓ Discovery & Excavations: While the artifacts were first noted by British geologist J.W. Gregory in 1919, excavation began in earnest in 1943 under the direction of Mary and Louis Leakey (assisted by Italian prisoners of war).

In the 1960s, Glynn Isaac continued his dissertation research, and since the 1980s, Dr. Rick Potts of the Smithsonian Institution has led an ongoing, highly detailed research project in collaboration with the National Museums of Kenya.

✓ The Acheulean Handaxe Culture: The sheer volume of tools found here represents the actual camping and activity places of early humans—specifically Homo erectus—who occupied the site consistently between 1.2 million and 400,000 years ago.

The teardrop-shaped handaxes and bifacial tools were the “Swiss Army knives” of the Paleolithic era, used for butchering animals, digging for tubers, and chopping wood. The staggering accumulation of these tools proves that the human species had a tropical origin and a deep cognitive evolution centered in the Rift Valley.

✓ The Homo erectus discovery: For decades, archaeologists found thousands of tools and animal bones, but no human remains. That changed in 2003, when the Smithsonian team discovered a partial hominin skull (including a brow ridge, frontal bone, and temporal bone) near a volcanic ridge known as “Lava Hump.”

Dated to approximately 900,000 years ago, the fossil belonged to a small adult Homo erectus. Researchers believe these early humans foraged for food near the water during the day but retreated to the rocky highlands at night to avoid predators.

✓ Butchery Sites & Megafauna: Olorgesailie contains specific butchery localities where stone tools are found mixed with the bone fragments of extinct animals. One remarkable excavation revealed an elephant butchery site dated to 990,000 years ago, featuring an extinct elephant (Elephas recki) surrounded by over 2,300 stone artifacts, with visible cut marks on its ribs and hyoid bone.

The Ancient Environment (Geology & Climate)

Today, Olorgesailie is a harsh, arid landscape of dusty plains and acacia scrub. However, geological records show that this basin has undergone massive environmental shifts over the last million years.

✓ The Extinct Paleolake & Volcanic Preservation: Between 1.2 million and 400,000 years ago, the basin was periodically filled by a large, shallow freshwater lake and wetlands that attracted abundant wildlife.

The impeccable preservation of both biological fossils and cultural tools is due to the heavy falls of alkaline volcanic ash from nearby Mt. Suswa and Mt. Longonot. This ash blanketed the area, sealing the artifacts in place and creating distinct stratigraphic layers that allow scientists to precisely date the site using argon isotope methods.

✓ Extreme Climate Variability: By analyzing diatomite (the white silica skeletons of lake algae) and carbon isotopes in ancient soil, scientists have tracked at least 16 major environmental shifts at Olorgesailie.

The region violently swung between deep lakes, shallow swamps, river channels, and dry C4 grasslands. A fascinating geological feature here is the “Red Beds”—brightly colored patches of sediment dating back 500,000 to 800,000 years.

These beds formed when intense droughts dried out the swamps, allowing underground peat fires to burn so hot that they melted the surrounding diatomite.

✓ The Evolution of Fauna: This extreme climate variability forced rapid evolutionary adaptation. Early in the site’s history, the basin was dominated by giant, specialized grass-eaters: the giant baboon (Theropithecus oswaldi), a massive zebra (Equus oldowayensis), and an aquatic hippo (Hippopotamus gorgops).

As the climate fluctuated wildly, these giant, specialized animals went extinct. By 360,000 years ago, they had been replaced by smaller, more versatile relatives (such as the modern baboon, zebra, and elephant) that could browse, graze, and travel long distances in search of water.

Ultimately, the handaxe-making Homo erectus was also replaced by early Homo sapiens, who created smaller, more complex tools to survive this ever-changing environment.

Notes

* Olorgesailie Pre-Historic Site Tour booking/reservation |Click Here
* Bookings for all-night tours are to be done through the Public Relations Office a week before the visit

Museum & Pre-Historic Site Walk 

✓ Guided Tours: The core experience of Olorgesailie is a compulsory guided walk with a trained museum educator or site guide (a tip for the guide is customary)
✓ Excavated Trenches & Exhibits: View stratified sediment layers that teach visitors about excavation techniques and climate change. The museum pavilion also features fossil bones of extinct giant baboons, elephants, and hippos
✓ Acheulean Handaxe Fields: Walk along a specially constructed raised wooden catwalk that allows you to view the world’s largest concentration of handaxes left in situ (in their original positions) without disturbing the artifacts

Olorgesailie offers a truly rustic and authentic off-the-grid experience. Because the site is located in a remote area managed by the National Museums of Kenya, the accommodation options are basic and affordable, making them perfect for travelers looking to disconnect.

The Bandas (Cottages): For those who prefer a roof over their heads, the site offers modest, grass-thatched Bandas. These rooms are simple but well-maintained, blending seamlessly into the surrounding environment.

Camping & Picnic Grounds: For the ultimate nature experience, visitors can pitch a tent under the vast Rift Valley sky. With no electricity or light pollution, the campsite offers some of the best stargazing in Kenya.

Facilities & Important Visitor Notes

✓ Washrooms: The site features clean, basic toilets and washrooms. The water provided in the showers is non-potable (not for drinking)
✓ Off-the-Grid: The site does not have electricity. Be sure to bring power banks to charge your devices and flashlights or headlamps to navigate the campsite at night
✓ Self-Catering is Mandatory: There are no restaurants, cafes, or shops at Olorgesailie. Visitors must bring absolutely all their own supplies, including food, cooking equipment, charcoal/firewood, and plenty of drinking water. The last reliable place to buy groceries is in Kiserian town before descending into the valley

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