EARTH SCIENCE Flashcards
He studied the relative positions of sedimentary rocks
a danish scientist
Nicholas Steno
Formed particle by particle and layer by layer.
The layers are piled on top of the other .
Rock layers are also called Strata and stratigraphy is the science of strata or layers.
Sedimentary rocks
These are basic principles that all geologists use in deciphering the age and characteristic of rocks layers.
Stratigraphic Laws
Stratigraphic laws
Most sediments when deposited, form a horizontal or nearly horizontal layers
The Principle of Original Horizontally
Stratigraphic laws
Rocks layers, as originally laid down, are bounded by the edge of the basin deposition
The Principle of Lateral Continuity
Stratographic laws
As undisturbed layers accumulate through time; older layers are buried beneath younger layers.
The Principle of Superposition
Stratigraphic laws
Was developed by William Smith, and English engineer in the late 1700’s.
This principle allows geologists to identify and correlate the ages of rock layers based on the fossils they contain.
The Principle of Faunal Succession
are procedures used by scientists to determine the age of rocks. Geologists establish the age of rocks in two ways: relative dating and absolute dating.
Dating techniques
Used to arrange geological events and the rocks they leave behind in a sequence.
Rock successions are sequences of rocks that are established by the order in which they are deposited.
*Cannot specify the absolute age, whether one rock is older or younger than another.
Relative dating
Refers to the use of animal bones to determine the age of sedimentary layers and the materials embedded within those layers.
Faunal dating
The term used to describe any dating technique that tells how old a rock specimen is in years
*Some scientists prefer the terms chronometric or calendar dating, as use of the word “absolute” implies an unwarranted certainty of accuracy.
Absolute Dating
A method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample
*By measuring the amount of radioactive decay of a radioactive isotope with a known half-life, geologists can establish the absolute age of the parent material.
Radiometric Dating
This technique measures the decay of C-14 in organic material and can be best applied to specimens younger than 60,000 years.
Radiocarbon dating
Uses a very important isotope which is U-238
*It is used in dating very old rocks, especially rocks that do not contain fossils.
Uranium dating
independent of all physical and chemical conditions such as temperature, pressure and chemical agents.
Radioactive dating
Scientists define (blank) as any trace of living creatures such as a recognizable structure or impression of a structure of an organism like skeleton, trails or fecal remains that are embedded in very old rocks which are at least 5000 years old.
Fossils
are the basis for defining boundaries in the geologic time scale and also for the correlation of strata.
Marker Fossils
By studying (blank), scientists were able to tell that the Earth has experienced different climates in the past.
Fossil record
is the chronology of the Earth’s formation, changes, development and existence.
Geologic Time
Is a system of chronological measurement that relates stratigraphy to time.
*It is used by geologists and paleontologists to describe the timing and relationships between events that have occurred throughout Earth’s history.
Geological time scale
an example of this is The boundary between the Permian and Triassic is marked by a mass extinction in which a large percentage of Earth’s plant and animal species were eliminated.
The Boundary “Events”
A series of mountain building, faulting and volcanic eruptions interrupted by erosion took place. Simple seaweeds and bacteria were the only forms of life known to have lived in this era.
precambrian era
The oceans rose as the climate became warmer and the glaciers melted. During this period, the continents rose because of great mountain building, volcanism, followed by erosion.
Cambrian period
Narrow seas began in the continents. About half of the continents were covered by the seas. Marine fossils formed in these continental seas. The continents again rose before the end of the period. The first animals with backbones appeared in the water environment.
Ostracoderms-bony armored animals-became abundant. No life had yet appeared on land.
Ordovician period
Volcanic eruptions on the sea floor and mountain building eventually caused the seas to fall back. The climate remained warm. Animals with backbones developed further in the seas. Sea scorpions about 3m long appeared. Corals became abundant. Sea plants developed more complex parts. Leafless plants appeared on land for the first time.
Silurian period
The first fish evolved. Primitive sharks about 20m long appeared.
This is the “Age of Fish”
Devonian period
Shallow seas spread in the continents. In other areas large swamps covered with giant trees over 35 m high developed. At the close of the period the giant trees died. Their decay and burial eventually formed the great coal beds that are now being mined.
Carboniferous period
continental seas were turned into wide lakes by folding of the Earth’s crust. Climate was mostly very cold with the Southern Hemisphere having widespread glaciers. Giant pine trees and other similar plants decreased in number.
Permian period
the continents were covered with vast desserts and high mountains. Widespread erosion formed great beds of sandstone in the shallow seas in and around the continents.
Triassic Period
The seas spread in continents again. The high mountains eroded in the Triassic period were reduced to low hills. The fish-like reptiles in the seas became abundant. A bird-like reptile developed.
Jurassic Period
Rivers flowed slowly on the eroded land to form huge deltas. The climate remained mild as in the Jurassic period. Flower-bearing plants evolved.
Cretaceous Period
violent earthquakes, volcanic eruptions and mountain buildings which began the formation of the Alps in Europe, the Himalayas in Asia, the Rockies in North America and the Andes in South America characterized the Period.
Paleocene epoch
The Alps, Himalayas, and Andes continued to grow. The Atlantic and the Indian oceans were formed, presumably through the drifting of continents. Seas spread in Southern Europe and Northern Africa.
Eocene Epoch
The Continents began to grow again. Mountain ranges continued to build up. A cycle of warm, mild and cool seasons became established. Forests occupied less land, while grassland increase in area. Grass eating mammals increased in number and variety. A primitive, tail less ape, probably the ancestor of human appeared.
Oligocene Epoch
Extensive movements of the Earth’s crust joined Asia with Europe and locked in the Mediterranean sea. Extensive erosion started to carved the Grand Canyon in North America. Climates were varied, warm in some parts and cooler in other parts.
Miocene Epoch
Mountain-building forming the Sierra Nevada and the Coast Ranges in North America began. Subsidence of land formed the North Sea, the Black Sea, The Caspian Sea, and The Aral Sea.
Pliocene epoch
Glaciers and ice spread and receded several times during the epoch. The increase of glaciers lowered the ocean level; the melting of glaciers raised the ocean level. Mammals and primitive people crossed land bridges exposed by the sinking water level.
Pleistocene epoch
Glaciers began to melt, causing the water level to rise again, thus separating the British isles from Europe. The climate became warm, formed more deserts. People developed in intelligence and learn to domesticate animals and cultivate plants.
Holocen/ recent Epoch
is the wearing away of the land by the sea often involves destructive waves wearing away the coast
Coastal erosion
is when destructive waves pick up beach material (e.g. pebbles) and hurl them at the base of a cliff. Over time this can loosen cliff material forming a wave-cut notch.
Corrasion
occurs as breaking waves, concentrated between the high and low watermarks, which contain sand and larger fragments wear away the base of a cliff or headland. It is commonly known as the sandpaper effect. This process is particularly common in high-energy storm conditions
Abrasion
Waves hitting the base of a cliff causes air to be compressed in cracks, joints and folds in bedding planes causing repeated changes in air pressure. As air rushes out of the cliff when the wave retreats it leads to an explosive effect as pressure is released
hydraulic action.
is when waves cause rocks and pebbles to bump into each other and break up
Attrition
a raised mass of land or rock that projects into a body of water, such as the sea. It is also known as a headland or peninsula.
A promontory
are responsible for some of the most amazing coastal landforms n the country and around the world.
Coastal processes
are the ways in which sediment is moved around the coast, and the resulting landforms they create. These processes are primarily controlled by physical forces, such as waves, tides, and winds.
Coastal processes
Erosion is the gradual breakdown of the land or coast due to unending wave action.
Erosion
when weak acids in seawater react with certain types of rocks, usually limestone and chalk slowly dissolve the rocks.
Corrosion
The movement of broken material by waves and tides.
Transportation
The release of eroded material when waves and tides lose energy.
Deposition
build beaches and are seen often during summer season.
Constructive waves
describes how long and how far the wind acted on the water.
Fetch
is mostly due to large fetch while small fetch produces small constructive waves and is responsible for deposition.
Coastal erosion
These waves have a strong swash and a weak backwash, which means they deposit more material than they take away.
Constructive waves
These waves have a strong backwash and a weak swash, which means they erode material.
Destructive waves
are a natural defense against coastal erosion by reducing the impact of waves, currents, tides, and storm surges. Simply they reduce wave damage from strong typhoons and tsunamis by their roots strongly bind soils together.
Mangroves
is an imaginary line in the map that connects all points having the same depth below a water surface.
isobath
is an abnormal rise of water generated by a storm, over and above the predicted astronomical tide.
Storm surge
the process of capturing and storing atmospheric carbon dioxide
Sequestration
examples of greenhouse gases are
carbon dioxide, methane and water vapor, ozone, nitrous oxide, chlorofluorocarbons
When water heats up, it expands. About half of the sea-level rise over the past 25 years is attributable to warmer oceans simply occupying more space.
Thermal expansion
are instruments that measure sea level changes by recording how high or low the water is at a given point on the coast.
Tide gauges
are instruments on satellites used to measure the height of the ocean surface from space. They work by sending radar or laser pulses down to the ocean and timing how long it takes for these pulses to bounce back to the satellite.
Satellite altimeters
