Page 166 - Sedimentology and Stratigraphy

Freshwater Lakes 153

Fig. 10.1 Hydrological regimes of lakes.
open, or are hydrologically closed with a low supply
of dissolved ions allowing the water to remain fresh.
Saline lakes are hydrologically closed and are pe-
rennial water bodies in which dissolved ions have
become concentrated by evaporation. Ephemeral
lakes mainly occur in arid climatic settings and are
temporary bodies of water that exist for a few months
or years after large rainstorms in the catchment area,
but are otherwise dry.

10.2 FRESHWATER LAKES
Fig. 10.2 A lake basin supplied by a river in the foreground,
with outflow through a sill to the sea in the distance. The majority of large modern lakes are freshwater:
they occur at latitudes ranging from the Equator to
the polar regions (Bohacs et al. 2003) and include
From a sedimentological point of view, three types some of the largest and deepest in the world today.
of lake can be considered, irrespective of their mode Lacustrine deposits from lakes of similar scales are
of formation or hydrology. Freshwater lakes have known from the stratigraphic record, mainly from
low salinity waters and are either hydrologically Devonian through to Neogene strata.