Get Your High School Diploma Online Science Discovery Series Olympus High School Jeff Taylor Science Instructor
Episode 1Sand Dunes and Sedimentary Rocks Paria Canyon, AZ How They Form
Grand Staircase-Escalante NM, UT Sandstone Sandstone are layers of sand-sized particles that are cemented together. The cement determines the strength of the sandstone. Sandstone can form from sand dunes, river or lake bottoms, or former beaches.
Great Sand Dunes NP, CO Sand Dunes Sand Dunes form where sand particles are blown in the wind and then pile up in a place where the wind slows. Rain trickles down to the bottom of the dunes. Minerals that dissolve in water cement the sand and solidifies the base.
Lithification Maui, HI These sand dunes have lithified when water seeped in and cemented the sand grains. Later, winds blew away the loose sand above.
Navajo Sandstone, Big Water, UT Sandstone Fossilized sand dunes can be determined by their cross-bedding. Cross-bedding are alternating layers that are tilted against each other.
The Dive, Grand Staircase-Escalante, UT Navajo Sandstone They formed in an ancient Sahara-like Desert some 75 million years ago
PlayasEvaporite Basins Carrizo Plain NM, CA Salts dissolve from rocks into rainwater Water gathers at the valley floor to form shallow lakes Hot summer evaporate the water, leaving just a flat salt layer This salt can be sodium chloride or a variety of alkaline substances like gypsum, calcite, or soda.
Gypsum Dunes White Sands NM, NM When evaporites from a dry lake are broken into small pieces and blown in the wind, they can pile up into dunes. At White Sands, NM the “sand” will dissolve in your mouth!
Vermillion Cliffs Wilderness, UT Lake or Ocean Sandstones Sandstone layers that are completely horizontal are usually formed at the bottom of lakes or the ocean.
Lake and Ocean Settling When sediment flowing down a river meet a lake, they drop out and settle to the bottom to form a flat layer.
Lake Sediments Here, changing lake levels leave horizontal beds of sediments. When buried, they will compact into stone.
Siltstones Siltstones are similar to sandstone, but the grains are much finer. They form at the bottom of the ocean and lakes where very small particles settle to the bottom.
Clays and Mudstones In the ocean or lake bottoms where microscopic particles settle, mud and clays cement together for form layered rock. Mudstones are strong and well cemented. Clays tend to be weaker and easily crumble.
HoodoosConglomerate Capping Sandstone Hoodoo’s form where strong rock protects weaker rock underneath
Volcanic Ash Volcanic ash can settle onto the ground or into lakes to form sediments.
Bentonite Clays Bentonite clays form when volcanic ash from eruptions lands in water. This ash mixes with the mud and organic matter for form a weak, puffy layer, that is extremely sticky when wet.
Evaporites When lakes or shallow ocean areas evaporate, they leave their salts behind. These salts form layers of crystals.
Tufa When springs in a soda lake emerge, they deposit their minerals in large pillars.
Evaporite Basin Water drains down into the basin. The water evaporates, leaving salts behind
Coal, Oil, and Natural Gas When organic matter such as dead plants get buried in mud it can be preserved as layers of coal. Oil and Natural gas pockets can also form under these layers, typically with the help of heat underground.
Petrified Wood and Fossils Hard organic remains such as tree trunks, bones, and teeth can be fossilized as their natural minerals get replaced by other minerals.
Fossils The calcium and carbon of Petrified wood and fossil bones are often replaced by quartz or magnesium.
Limestone When the shells of clams, snails, or coral reefs are preserved in the ocean sediments, limestone forms. Limestone is made of Calcium Carbonate. Limestone is a sure sign that an area was tropical once.
Travertine Limestone dissolves in water. Where water trickles down into the layers, it eats away at the rock forming caves and sinkholes. When the water drips in the caves and evaporates, it leaves the limestone behind again forming Stalactites.
Limestone Continued… Since limestone dissolves in water, it forms steep and interesting landscapes due to erosion.