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