In the late 1980s the site was used to dispose of cow carcasses suspected of having BSE in an unlined pit.

The three unlined pits were used for 'dilute and disperse' disposal of waste; accordingly they are continually releasing leachates into the groundwater.

Ecuadorean indigenous groups said Texaco dumped more than 18bn gallons (68bn litres) of toxic materials into unlined pits and rivers between 1972 and 1992.

From 1945 to 1969, they were poured into seven unlined pits.

A great profusion of unlined pits (bothroi) was characteristic of this phase: eventually they became filled with waste matter, bones, potsherds, even whole pots.

The chemicals were stored in 23 unlined pits and, the Environmental Protection Agency said, later contaminated the soil and ground water.

Even if the emulsions were reclaimed, the environmental damage from placing tars in unlined pits remained.

A small ash-charcoal lens and an unlined pit of 18 in.

The second type of cultural feature was an unlined bowl-shaped pit found in Stratum 4.

- Evidence of oil firms dumping contaminated soil in unlined pits.