Transcript Sedimentary-Rocks-with-notesheety

Sedimentary Rocks
• form from pieces of other, existing rocks or
pieces of once living things called
sediments
• form a thin layer over 75% of Earth’s
surface
Lithification
is the process that converts
sediments into rock. It is a five step
process that begins with weathering.
Weathering → Erosion → Deposition
→ Compaction → Cementation
Lithification is a VERY slow process.
Weathering
Weathering ONLY occurs on the surface!
Weathering is a chemical or physical
process in which rocks are worn down by
water, wind, ice, gravity, and organisms.
There are two types of weathering,
mechanical and chemical.
Erosion
The second step in the lithification
process is erosion, in which sediments
and organic material are moved by water,
wind, ice, gravity and sometimes even
organisms.
Deposition
The now weathered and eroded
pieces of sediment are deposited or
dropped off somewhere else on the
Earth’s surface.
The Law of Superposition states that
if the layers of sediment are not
disturbed, the oldest rock will be at
the bottom and the youngest on top.
Compaction
This is the process in which layers of
sediment that have built up over time
are pressed and squeezed together.
Cementation
• the last step in the lithification process
• mineral crystals “glue” sediments together
and give the rock its color
Size of Sediment = Type of Rock
Clastic Sedimentary
• Made from pieces of
other rock
• Conglomerate (top)
has rounded
sediment
• Breccia (bottom) has
more angular
sediment
Clastic Sedimentary
• Sandstone (above) is made
from grain-sized sediment
• Shale (top right) and Mudstone
(bottom right) are made from
clay and silt sized sediment
Organic Sedimentary
• made from remains
of plants and
animals
• Chalk (top) is made
from grains of tiny
sea creatures.
• Limestone (middle)
is made from coral
reefs and other
marine material.
• Coal (bottom) is
made from
decayed plant
material.
Chemical Sedimentary
• form when minerals
come out of solution
(precipitate) or are left
behind after evaporation
• Halite (top) is rock salt
created from salt water.
• Limestone (middle) is
made from precipitated
minerals.
• Geodes (bottom) are
made from minerals that
crystallize inside a
hollow space.
Gemstone Formation
Gemstones
associated with
sedimentary rock
include jasper,
malachite, opal and
zircon.
Unique Features
Stratification – visible bands
that result from layers of
different sediment being
deposited one atop another.
The oldest layers are
always at the bottom. This is
the Law of Superposition.
Zhangye Danxia Landform: Gansu, China 20 million years old
Unique Features - Fossils
Petrified Forest National Park, Nevada
Petrified Wood, Nevada
Stonehenge, England
(sandstone - clastic)
Arches National Park, Utah
(banded sandstone - clastic)
The elephant rock formation in Valley of Fire State Park in
Nevada is natural sandstone (clastic)
Wulingyuan Scenic Area in Zhangjiajie, China is a
100 square mile area containing thousands of sandstone
pillars described as nature's version of skyscrapers. Some
are taller than the Empire State Building! (clastic)
Koekohe Beachon South
Island, New Zealand
Maori legend has it that the
Moeraki Boulders
scattered along the beach
are the remains of eel
baskets, gourds, and
sweet potatoes from a
large canoe wreck.
Scientifically, the spherical rocks are the result of a natural
process known as concretion, where grains of sand and stone
combine to form these masses. Reaching a diameter of up to
six feet, these boulders dot the eroded Otago coastline.
(clastic)
12 Apostles in Australia (clastic)
Smithsonian Institution, Washington, DC
(sandstone - clastic)
Tasmania's Maria Island includes the
swirling, Triassic-era limestone of the
Painted Cliffs. (clastic)
Bryce Canyon Utah is made of layered red and orange
rock pillars, known as hoodoos. (clastic)
White Cliffs of Dover, England
(organic)
Guadalupe Mountain, Texas
(organic limestone)
Irish Peat Bogs
Irish Cottages were/are heated with peat.
Peat Bricks
The Blue Grotto, Capri, Italy (organic)
The Blue Grotto
The blue coloration is due to light reflection off of the
limestone formations below the water of the grotto.
Bonneville Salt Flats, Utah (chemical)
Salar de Uyuni in Bolivia is the largest salt flat in the world. When dry, the flat
is a perfectly horizontal sheet of hexagonal salt tiles. During the wet season,
the shallow lake perfectly mirrors the sky, creating an illusion of infinity.
(chemical)
The Badwater Salt
Flats in California
lowest point in
the U.S. at
282 feet below
sea level.
(chemical)
Caves
(chemical limestone)
Striped Icebergs! Are these
sedimentary rocks?