 The natural water content of the clay was above the liquid limit in some areas and above the plastic limit in others.Due to the salt concentration within marine clays, which would have crystallized as the marine water receded historically, the salt would be removed by rainfall and meltwater after winter.Glacio-marine clays and silts are common in this area due to the prior existence of the Champlain Sea, which used to occupy the St. Lawrence and Ottawa valleys post-glaciation.