Studied by 6 peopleFossils
________- are the remains or traces of prehistoric life.
Angiosperms
________- flowering plants with covered seeds- replaced gymnosperms as the dominant land plants.
Carbonization
________ is particularly effective in preserving leaves and delicate animals.
Earth
________ is much older than anyone had previously imagined and that its surface and interior have been changed by the same geological processes that continue today.
Laurasia
________- is the continental mass that formed the northern portion of Pangaea, consisting of present- day North America and Eurasia.
Radioactivity
________- is the spontaneous decay of certain unstable atomic nuclei.
population of organism
○ It refers to the cumulative change in a(n) ________ over time.
columns of calcium
They are distinctively layered mounds or ________ carbonate.
Gymnosperms
________ are seed- bearing plants that do not depend on free- standing water for fertilization.
Trace fossils
________ are indirect evidence of prehistoric life.
Oxygen
________ began to accumulate in the atmosphere about 2.5 billion years ago.
Eons
________- represent the greatest expanses of time.
Uniformitarianism
________- the forces and processes that we observe today have been at work for a very long time.
Molds
________ and casts are another common type of fossil.
Correlation
________- is establishing the equivalence of rocks of similar age in different areas.
Mammals
________- animals that bear live young and maintain a steady body temperature- replaced reptiles as the dominant land animals in the Cenozoic era.
fine sediment
It occurs when an organism is buried under ________.
Shields
________ are large, relatively flat expanses of ancient metamorphic rock within the stable continental interior.
geological change
Revived Hutton's principle of slow ________, and presented a classic explanation of development over millions of years.
water dwelling
The elimination of a(n) ________ stage (like the tadpole stage in frogs) was an important evolutionary step.
Radiocarbon Dating
________- is the method for determining age by comparing the amount of carbon- 14 to the amount of carbon- 12 in a sample.
◆ Dinosaurs
________ were land- dwelling reptiles that thrived during the Mesozoic era.
Earths original atmosphere
________ was made up of gases similar to those released in volcanic eruptions today- water vapor, carbon dioxide, nitrogen, and several trace gases, but no oxygen.
Radiometric dating
________ has supported the ideas of James Hutton, Charles Darwin, and others who inferred that geologic time must be immense.
Law of superposition
________- states that in an undeformed sequence of sedimentary rocks, each bed is older than the one above it and younger than the one below it.
negative electrical charges
◆ Orbiting the nucleus are electrons, which are ________.
accurate radiometric date
A(n) ________ can be obtained only if the mineral remained in a closed system during the entire period since its formation.
angular unconformity
A(n) ________ indicates that during the pause in deposition, a period of deformation (folding or tilting) and erosion occurred.
radioactive isotope
Each ________ has been decaying at a constant rate since the formation of the rocks in which it occurs.
Inclusions
________ are rocks contained within other rocks.
Cenozoic era
◆ The ________ is divided into two periods of very unequal duration, the Tertiary period and the Quaternary period.
Half life
________- is the amount of time necessary for one- half of the nuclei in a sample to decay to a stable isotope.
geological events
Rocks record ________ and changing life forms of the past.
important components of sediment
They are ________ and sedimentary rocks.
gymnosperms
The ________ quickly became the dominant plants of the Mesozoic era.
Relative dating
tells us the sequence in which events occurred, not how long ago they occurred
Law of superposition
states that in an undeformed sequence of sedimentary rocks, each bed is older than the one above it and younger than the one below it
Principle of Original Horizontality
means that layers of sediment are generally deposited in a horizontal position
Principle of Cross-Cutting Relationships
states that when a fault cuts through rock layers, or when magma intrudes other rocks and crystallizes, we can assume that the fault or intrusion is younger than the rocks affected
Correlation
is establishing the equivalence of rocks of similar age in different areas
Fossils
are the remains or traces of prehistoric life
Unaltered Remains
Some remains of organisms-such as teeth, bones, and shells-may not have been altered, or may have changed hardly at all over time
Two conditions are important for preservation
rapid burial and the possession of hard parts
The principle of fossil succession
states that fossil organisms succeed one another in a definite and determinable order
Index Fossils
are widespread geographically, are limited to a short span of geologic time, and occur in large numbers
Interpreting Environments
Fossils can also be used to interpret and describe ancient environments
Radioactivity
is the spontaneous decay of certain unstable atomic nuclei
Half-life
is the amount of time necessary for one-half of the nuclei in a sample to decay to a stable isotope
Radiocarbon Dating
is the method for determining age by comparing the amount of carbon-14 to the amount of carbon-12 in a sample
◆ There are three eras within the Phanerozoic eon
the Paleozoic, which means "ancient life," the Mesozoic, which means "middle life," and the Cenozoic, which means "recent life."
Stromatolites
The most common fossils
Following the long Precambrian, the most recent 540 million years of Earths history are divided into three eras
Paleozoic, Mesozoic, and Cenozoic
Laurasia
is the continental mass that formed the northern portion of Pangaea, consisting of present-day North America and Eurasia
Angiosperms
flowering plants with covered seeds-replaced gymnosperms as the dominant land plants
Note
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