Stone heave field experiment in sand

Movements of 24 cm large globes and cuboids of granite, concrete and wood were recorded during four and a half years. The objects were buried at three different depths in well-sorted sand in a natural cool temperate environment. All objects moved during the experiment and at the end most wood objects, which had a relatively low thermal conductivity had moved up, and the granite and concrete objects with higher thermal conductivities had sunk a little or remained almost in place. Also the soil surface moved and its final height was up to 1 cm above that at the start. The movements of the objects started within a few hours after temperature shifts around 0 °C with the granite reacting more readily than the wood. It is hypothesized that the movements are related to the thermal properties of the objects and the soil. The experiment was done in parallel with an experiment in clayey silt and the net results in sand show clear parallels to the movements of similar objects in the silt. It is concluded that the material and shape of the object are more important to movements than whether they are embedded in sand or silty clay.

Research Highlights► Granite, concrete and wood objects in sand responded quickly to shallow frost. ► Granite, with its higher thermal conductivity, responded more readily than wood. ► After more than 4 years wood objects had moved up and granite objects down. ► Strong parallels were found in movements of similar objects in sand and silt. ► Hypothesis: H2O vapour moves from air and soil and accumulates as ice in topsoil.