Sclerochronology is the study of physical and chemical
variations in the accretionary
hard tissues of invertebrates and coralline red algae, and the
temporal context in which
they formed. The term was coined in 1974 following pioneering
work on nuclear test
atolls. It comes from the three Greek words scleros - hard,
chronos - time and logos -
science, and refers to the science of ordering events in
time.
Sclerochronology focuses primarily upon growth patterns
reflecting annual, monthly,
fortnightly, tidal, daily, and sub-daily (ultradian) increments
of time. The regular time
increments are controlled by biological clocks which - in turn -
are entrained by
environmental and astronomical pacemakers.
Familiar examples include annual bandings in reef coral
skeletons or annual, fortnightly,
daily and ultradian growth increments in mollusk shells as well
as annual bandings in
fish otoliths. Sclerochronology is analogous to
dendrochronology, the study of annual
rings in trees, and equally seeks to deduce organismal life
history traits as well as to
reconstruct records of environmental and climatic change through
space and time.