hiekkamassaa

Hiekkamassa is a geological term used in Finland to describe a body of loose, unconsolidated sand that forms a distinct mass within a sedimentary sequence or on the landscape. It consists mainly of sand grains, often well sorted, with limited cementation. The term covers sand bodies of varying size, from small deposits to larger sand-rich units embedded in glaciofluvial, coastal, or riverine sediments.

Formation and setting: Hiekkamassa forms where sand is deposited by meltwater, rivers, or wind and later preserved as a separate body within other sediments. It may occur as dune fields, sand sheets, river terrace sands, or sand-rich layers within eskers and deltas. Over time, burial and limited diagenesis may slightly cement the grains, but the rocks remain largely unconsolidated.

Properties: It typically has high porosity and permeability, low cohesiveness, and is prone to erosion and movement when exposed. Saturated sand masses can lose strength and, in some circumstances, experience liquefaction during seismic shaking.

Distribution and significance: Hiekkamassa is common in regions with historical or present sand-rich deposits, including areas shaped by glacial outwash and coastal processes. The presence of hiekkamassa affects groundwater flow, foundation design, and land-use planning, especially near shores and rivers.

Etymology: The name derives from hiekka (sand) and massa (mass). In geological literature, variants or region-specific terms may be used.