Flashcards in Earth History Deck (30)
What is angular nonconformity?
Indicates deposition of sediments, tectonic uplift, and deformation, erosion and deposition of new sediments
What are Carbonaecous films?
Thin silhouettes of carbon. Result from high temp and press. as sediments deposit on top. Carbon of organism undergoes chemical change to produce thin carbon film
What are climate proxy records?
Historical records of crop productivity and other phenomena that imply the nature of past climate. Ex: Tree rings
Principle of Superposition
In any sequence of sedimentary strata the order in which the strata were deposited is from bottom to top
A.k.a Older rocks on bottom, younger rocks on top
What are embedded fragments?
The law of included fragments is a method of relative dating in geology. Essentially, this law states that clasts in a rock are older than the rock itself. One example of this is a xenolith, which is a fragment of country rock that fell into passing magma as a result of stoping.
How may volcanoes have helped to cause the relative warmth in the Cretaceous Period?
Increased volcanic activity, may have contributed to more climate warming and sea level rising
How recent did Humans exist?
One hundred thousand years ago
What are index fossils and what are their characteristics?
Fossilized organism remains and can can be used to correlate rock layer.
Must be abundant, widespread, unique and brief period existence
In what period did dinosaurs become completely extinct?
In what period did mammals first appear?
In what period did reptiles first appear?
In what period did the first amphibians appear?
In what period did the first flowering plants appear?
Principle of Cross-cutting relationships?
That the geologic feature which cuts another is the younger of the two features. It is a relative dating technique in geology.
How does Radioactive dating work?
By measuring the amount of parent and daughter isotope within a rock or mineral and use the ratio of the two to find age of rock
Where are the oldest known rocks on Earth?
Found in the Canadian Shield
What is walking the outcrop?
Outcrop - A section of a rock layer that can be seen at Earth's surface
Walking along the outcrop is used to find out if 2 rock layers are the same. Can be diff. in areas of thick soil or vegetation
What are trace fossils?
Impressions such as bite marks, burrows, tracks and trails in stone. Indirect evidence
What are four factors that could contribute to global warming?
Earth's Motion, Plate Tectonics, Volcano eruptions and sunspots
What are the divisions of the geologic timetable based upon?
A summary of major events from analyzing the rock record. Based on evidence particularly fossil evidence
What are the ways that remains can be persevered as fossils?
Original Remains: Unchanged parts or complete parts of animals and plants. Woolly mammoths found in Alaska and Siberian in permafrost, woolly rhinos in Poland in asphalt. Occur in mud to shale or resin to amber
Replaced Remains: Water can remove soft parts and replace them with minerals
Molds and Casts: Molds are depression of organism in rock and cast are minerals filling mold and solidifying
Trace Fossils: Impressions such as bite marks, burrows, tracks. Indirect evidence
Carbonaceous Films: Thin silhouettes of carbon. Result from high temp and press. as sediments deposit on top. Carbon of organism undergoes chemical change to produce thin carbon film
What are the orders of geological time?
Eons, Eras, Periods, Epochs
What is Petrified wood?
Replaced Fossil. Silica replaces woody structure and preserves wood with rings in tact
What are the two ways that volcano can affect climate?
1) Release sulphur dixoide into atmosphere which creates sulphurous acid
2) Mass releases of CO2
What do fossils of tropical plants in Greenland provide evidence for?
Greenland was once closer to the equator. Proves plate tectonics as something causes climate change
What is Relative dating?
An order of sequence of events as they occured. Can not identify actual dates
What is the earliest known glacier?
Tillite is a rock created from deposits of till cementing together. Some are 2.3 billion years
What gas is abundant now in the atmosphere but not very abundant in Earth's primitive atmosphere?
Hydrogen and Helium, Water Vapour, Carbon Dioxide, Oxygen and Nitrogen
What things would the change in the location of a continent affect?
Amount of solar radiation reflected back to space from land and water