Terraces have been found in a kettle and thus indicated that remnant blocks of ice still existed as base level abruptly changed. After the weight of the ice is relieved by melting, mantle material flows back and the land rises. Rapid fluctuations in the climate and the location of unmelted ice will influence uplift. By dating the age of shells in the terraces with the C14 method , we can estimate the rate of uplift movement. This in turn allows geoscientists to estimate the rheology of the mantle.
Rheology is the study of how materials flow.
Although the mantle is solid, it flows like a liquid but very slowly.