Those deposits are called tillites and they’re the material that gets left behind by glaciers.
这些沉积物被称为硅藻土,它们是 冰川留下的物质。
英语百科
Till
(重定向自Tillite)
Till or glacial till is unsorted glacial sediment.
Till is derived from the erosion and entrainment of material by the moving ice of a glacier. It is deposited some distance down-ice to form terminal, lateral, medial and ground moraines.
Till is classified into primary deposits, laid down directly by glaciers, and secondary deposits, reworked by fluvial transport and other processes.