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Conglomerate
A coarse-grained sedimentary rock consisting of rounded pebbles that
are surrounded by finer grained rock fragments.
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This conglomerate of an assortment of well-rounded clasts (note
plutonic-rock clasts) outcrops near Presque Harbour, Placentia Bay.
The matrix in this conglomerate constitutes a very small proportion
of the rock and is restricted to the space between clasts.
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Sandstone
A sedimentary rock composed of mostly sand-sized particles, usually
cemented by calcite, silica or iron oxide.
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This sample of alternating light sandstone and dark siltstone beds is
from the Gander Lake area of Central Newfoundland. Note erosion of
the tops of the fine-grained siltstone beds by the sandstone, and
grading in the sandstone. These sedimentary rocks form part of a
flysch sequence.
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Siltstone
A fine-grained sedimentary rock mostly composed of silt-size particles.
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The photo, from the Gander Lake area, shows dark siltstone interbedded in a
rhythmic fashion with white sandstone beds. These sedimentary rocks form
part of a flysch sequence. The beds were originally deposited nearly
horizontal, but are vertically dipping now because of folding.
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Shale
A fine-grained sedimentary rock formed from mud or clay.
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This thin-bedded, red shale, which exhibits a slaty cleavage, is
located in the Newfoundland interior 30 kilometres north of the
community of Grey River.
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Limestone
Limestone is a sedimentary rock composed of mostly calcium carbonate
that formed by chemical precipitation from seawater or by the
accumulation of fossils, such as shell, coral and algal mounds.
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Limestone beds in the photograph comprise domal- to subspherical-shaped
mounds (stromatolites) consisting of calcium carbonate and silt.
These mounds were part of a colony of blue-green algae that lived
during the Cambrian period. These examples occur near Flower's Cove,
western Newfoundland.
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