Morainal sediments are deposited directly by glacial ice and their structure varies from relatively loose near the surface, to very compact at depth. This is related to the origin of the till: the more compact and fine matrix till was deposited as basal (or lodgement) till under the glacier, whereas the less compact and coarser ablation till was deposited by melting of ice. The finer particles of the upper till are commonly washed away by meltwater from the glacier and deposited in lacustrine and marine environments.