Download Paleozoic, Late Silurian Period, 420 Million Years Ago

Origin of Planet Earth
420
Paleozoic
LATE SILURIAN PERIOD
420 MILLION YEARS AGO
MORE SCIENCE FACTS
In Silurian time the tropical seas of the Waterloo Region
were teeming with life, including corals, brachiopods (lamp
shells), trilobites, fish, marine scorpion-like animals, known
as eurypterids, and crinoids. Crinoids are related to
sea-urchins and starfish and they are alive in today's oceans.
The illustration shows a group of near-complete Silurian
crinoids and the remains of their stems as you might see
them in the Elora Gorge, at Rockwood or near Cambridge.
The Silurian is the third period of the Paleozoic.
The Silurian Period is named from rocks in South Wales
in the tribal area of the Silures.
By Late Silurian time the shallow oceans in this part of
North America had dried up and minerals such as gypsum
and salt were being deposited in salt pans (left). Thin beds
of gypsum and salt belonging to the Salina Formation are
present about 70 - 105m (230 - 344 feet) below you.
Gypsum was mined at Drumbo, near Innerkip and is being
mined near Caledonia. Salt is recovered from thick deposits
near Windsor and Goderich.
Silurian rocks form the top of the Niagara Escarpment
and outcrop farther west in areas at Elora Gorge (top),
the Rockwood Conservation area (bottom) and near
Cambridge.
Silurian Rocks are present 70 - 220m (230 - 722 feet)
below you.
Middle Silurian rocks contain the remains of animals that
lived in a sub-tropical sea about 30 degrees south of the
equator at that time. Small reef structures in these rocks
are drilling targets for the oil and gas accumulations
formed from the remains of the animal communities.
The GeoTime Trail
Project has been
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Concept, text and illustrations: Dr. Alan V. Morgan