Transcript Formation of Sedimentary Rocks

Formation of Sedimentary
Rocks
Section 6.1
Weathering
 Weathering – a set of processes
that breaks rock into smaller pieces
 Sediments – pieces of rock that are
moved and deposited by water, wind,
glaciers, or gravity
 Sediments are “glued together” to
form sedimentary rocks
 Sediments can range greatly in size
Weathering
 Compare and contrast physical and
chemical weathering.
 Rock fragments break off along
fractures or grain boundaries
Erosion
 Erosion is the removal and transport
of sediments
 4 agents include
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Wind
Water
Gravity
Glaciers
 Eroded material is almost always
moved downhill
Deposition
 Deposition occurs when transported
sediments are deposited on the
ground or sink to the bottom of a
body of water
 Deposition occurs when transport
stops
 The largest grains will settle at the
bottom with the smaller grains at the
top – sorted deposition
Energy of Transporting Agents
 Fast-moving water transports large
particles better than slow moving
water
 Wind can move only small grains
 Glaciers move all sizes with equal
ease and deposited unsorted
 Landslides deposit sediments downhill
in a jumbled mass
Sedimentary Features
 Ripple marks form when sediment is
moved into small ridges by wind or
wave action or by river current
 Symmetrical vs. Asymmetrical
 The amount of rounding is
influenced by how far the sediment
has traveled
 The harder the mineral, the better
chance it has of becoming rounded
Sedimentary Features
 Fossils are preserved remains,
impressions, or evidence of onceliving organisms
 Organisms die and are buried before
they decompose
 What information can fossils provide?