Conservation Program

In 1993 the Conservation Institute entered into a formal agreement with the Tanzanian government to jointly take on conservation of the trackway. By July a full condition assessment and field testing were underway in order to plan a conservation program for the site. A site was established to test herbicides for killing acacia trees and for evaluating geotextiles as a root deterrent under reburial conditions. Off-site tests were also carried out on exposed tuff surfaces to determine the most appropriate materials for consolidating fragile tuff and to assess the feasibility of creating a new mold of the trackway.

The condition assessment confirmed the fragile nature of the tuff and led to the unanimous decision, endorsed by the consultative committee, that reburial was the most appropriate long-term conservation strategy for preserving the trackway. The testing also indicated that making a new mold of the trackway surface might endanger the footprints.

The 1994 season at Laetoli focused on mapping and stabilizing the site, constructing gullies and berms to reduce erosion from rain water, and killing the trees growing on and adjacent to the trackway in preparation for re-excavation and conservation in the upcoming year.

The first major conservation campaign in 1995 involved re-excavation, conservation, documentation, scientific study, and reburial of the southern 10 meters of the trackway, where the best-preserved footprints were found in 1979. Excavation revealed 29 hominid footprints and numerous hipparion, lagomorph, and carnivore prints. Thirty-eight acacia trees were found growing within the 10-by-4.5-meter trench. Four of the hominid prints were damaged by root growth.

The second conservation campaign took place in 1996, when the remaining 20 meters of the middle and northern trackway were excavated, conserved, documented, and reburied according to the methodology established for the 1995 season. Excavation of this section revealed 23 hominid footprints with discernible morphology, 18 hipparion prints, and over 145 lagomorph prints. Thirty-six acacia trees that had grown since 1978 were inventoried within the excavated trenches. The hominid prints in the northern trackway were not as well preserved as those in the south due to natural weathering and erosion of the volcanic tuff prior to their original excavation in 1978. Two prints at the northern end of the trackway were lost to erosion of the shallow 1978 reburial mound by surface runoff.

Conservation of the excavated trackway began with detailed condition recording of footprints and included treatment or removal of all roots and tree stumps. When conservation and documentation were complete, the trackway was reburied under multiple layers of sand and soil from the surrounding area, separated by geotextiles. The fill was sieved to remove coarse material and acacia seeds. The mound was topped with a layer of local soil and a bed of lava boulders to provide a physical armor for the reburial fill. Additional berms and stabilization measures were undertaken in 1996 to 1997 to divert runoff away from the trackway and protect the reburial mound from erosion.

Beginning in 1994, silicone rubber molds and polyester casts were made of existing 1978–79 casts, continuing in 1996 with patination of a cast of the southern part of the trackway for use in the Dar es Salaam National Museum and the making of an archival epoxy cast. The hominid prints were documented through photography and photogrammetry. Under separate permit from the Department of Antiquities, a three-member team consisting of one geologist and two anatomists conducted a restudy of the taphonomy, morphology, and gait of the prints in 1995 and 1996.

To involve the local Maasai community in the protection of the site, numerous meetings were held with Maasai elders from nearby villages beginning in 1994. This initiative led to a ceremony attended by the local communities in which the trackway was blessed by the traditional religious leader, the Oloiboni, to enhance its value to the Maasai. Two local Maasai guards were permanently posted to the site by the DoA.