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cuticle assemblages to a precision of 1
C (Livingstone and Clayton, 1980 ) and from
temperature sensitive pollen taxa, diatom and ostracod taxa, ostracod trace element
geochemistry and oxygen isotope analysis of aqueous carbonates (see Chapter 7 ).
Precipitation cannot be inferred directly but can be estimated from geomorphic evid-
ence of rising or falling lake levels, as well as from diatom and ostracod assemblages,
ostracod trace element geochemistry, stable oxygen isotopes and minerals present as
indicators of salinity (Fontes et al., 1973 ; Cerling et al., 1977 ; Fontes et al., 1985 ). Sed-
iment laminations and growth layers in oyster shells, mollusca, fish otoliths (Bowler
et al., 2011 ) and stromatolites all offer useful clues to seasonal changes. Wind direc-
tion can be deduced from evidence of upwelling recorded in the diatom assemblages
and from evidence of anoxic conditions revealed in organic matter, such as sapropel
layers (Mee et al., 2007 ). Cloudiness is hard to assess but may be inferred from
light-sensitive diatom assemblages.
°
11.5 Dating global fluctuations in lake level
One approach to judging the response of lakes in different latitudes to former hydro-
logical changes is that of Street and Grove ( 1976 ; 1979 ), who prepared time series
maps of global lake levels during the late Quaternary. Their pioneering work on the
paleoclimatic significance of African lakes (Street and Grove, 1976 ) was later exten-
ded to all continents (Street and Grove, 1979 ). They found that the majority of lakes
in the intertropical zone were low or dry during the LGM but were high once more
during the early to mid-Holocene. This is a useful first-order approach in documenting
desert lake histories, but it depends on very tight chronological control and cannot
take account of local forcing factors, such as locally perched water-tables or changes
in run-off linked to changes in surface cover. For example, in the southern Negev
Desert, Yaır ( 1994 ) found that run-off is higher today on bare rocky slopes in the
more arid southern Negev than it is on the loess-mantled slopes of the central and
northern Negev, where infiltration rates are high.
Another factor that needs to be considered when seeking to use lakes as paleocli-
matic indicators concerns the influence of extreme events. The scablands of South
Dakota bear witness to the sudden discharge from glacial lake Missoula and are of
minimal use in interpreting local climate at that time (Baker, 1978 ; Baker and Bunker,
1985 ; Teller, 1995 ). One increasingly exploited archive is the use of evaporite deposits
in saline lake basins, because these have excellent potential to record even quite brief
climatic fluctuations in the form of solution and precipitation cycles (Wasson et al.,
1984 ; Enzel et al., 1999 ). A perennial problem concerns the influence of old carbon
on the radiocarbon ages and the need to determine the reservoir effects as accurately
as possible (see Chapter 6 ). One approach, used by Prasad et al. ( 2009 ), involved
counting annual varves in Late Pleistocene Lake Lisan (the precursor to the modern
Dead Sea), which revealed variations in the reservoir age over time.
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