Why do engineers need to know about geologic time ?
Geolgical time is a method of ordering and measuring past events. The ordering
of events uses a group of observational methods known collectively as:
Measuring techniques rely on looking at geological processes with a strong
annual signature (eg. growth rings in various organisms) or on processes
that occur at a constant and measureable rate (eg. radioactive decay). These
The importance of "time" in engineering geology is in providing estimates
of frequencies for rare events such as floods, volcanic eruptions, and
earthquakes. Landslides can be dated and the rates of mass-wasting determined
for studies of coastal erosion and valley slope recession.
Geological time periods have been given names that correspond to segments of
the distant past. These names were appropriate when few absolute ages were
known but relative ages could be assigned (mainly by analysis of the fossil
record). The names are now part of the technical literature and popular
culture (Jurassic Park).
As radiometric methods become increasingly refined, the "dates" associated
with the names are modified so it is impractical to use the absolute dates
in most cases.
(c) Department of Civil and Geological Engineering, University of Saskatchewan,
57 Campus Drive, Saskatoon, SK, Canada, S7N 5A9