Once the heads of the main posts have been notched so that flooring, walls or ridge beam can be set into them, the foundation posts are ready to be driven.

To do this, it is important to know that lake marl becomes fluid when it is agitated, and quickly becomes solid again once the vibrations have stopped. Thus, one man can drive a post up to 2 meters deep without using the modern technique of striking the post on the head. Here, the genius of the Neolithic builder lay in knowing the properties of lacustrine sediment and how to best work with it, in order to drive posts that would be capable of supporting loads of several hundred kilos each.

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Driving the posts.

Notched head of a post.

Clairvaux, La Motte-aux-Magnins, 30th century BCE.

Stratigraphic section with posts.

Clairvaux, La Motte-aux-Magnins.