During the mid-1800's at the Kosapsom site (DCRu4), a school yard was built with a garden and playground area for children. Unfortunately, much of the top-soil the children played with (about 30 cm) was mixed with artifacts dating several thousand years old. Because of this, much of the upper layers at the Kosapsom site were not in situ. This means that dating the prehistoric artifacts was and is impossible, because the artifacts were not in their original places.
Like many archaeological sites in British Columbia, Kosapsom is a shell midden (a pile of shells discarded by people) area. This is a bonus for archaeologists because shells are alkaline. This helps to preserve the bones in the area which would normally rot and be lost forever. This alkaline soil preserves bones like deer, elk, sea-lion, beaver, seal, dog and fish. This preservation allows archaeologists to interpret what the people ate and how they survived thousands of years ago.
Glossary terms: Shell Midden, Alkaline.
Some archaeological pits have orange-sand-coloured soil. This type of soil is usually compacted ash from fires that is mixed with burnt shell, burnt bone and charcoal. Fire-cracked rocks (formerly cooking stones) are littered throughout this type of layers and indicate the former presence of a hearth.
Layers that are relatively thick with whole shells probably accumulated through dumping. Likewise, layers which show black soil that feels greasy to the fingers and crushed shell are most likely layers of a living surface where the people rested, ate and talked.
At the bottom of some pits we have what is known as sterile soil. This is commonly a yellowish-grey clay that was formed around 5000 years ago when the sea levels rose and turned the Gorge from a stream into an arm of the ocean.
Although shell middens are excellent sites for preserving bones, they are not good at preserving wood. Dry sites like Kosapsom are missing perhaps 90% of the wooden artifacts, such as houses and canoes.
