ROCK FORMATION, HISTORY OF THE EARTH, RELATIVE AND ABSOLUTE DATING Flashcards
are remains of organisms that lived
prior to the last glacial period about
10 000 years ago.
FOSSILS
Fossils are usually seen in ______
rocks because as organisms die, their remains will sink at the
bottom and will eventually be covered with sediments
SEDIMENTARY
The current geologic processes, such as volcanism, erosion, and weathering are the same processes that were at work in the past
Principle of Uniformitarianism
➢ Branch of geology
➢ Deals with the description, correlation and
interpretation of stratified sediments and
stratified rocks on and within the earth
➢ Study of rock layers
STRATIGRAPHY
The formation of sedimentary rock
layers is because of
STRATIFICATION
is the study of these rock layers.
STRATIFICATION
are used by geologist in conducting
relationship of rocks or rock layers
STRATIGRAPHIC LAWS
The law states that layers of sediment were originally
deposited horizontally under the action of gravity. It suggests that all rock layers are originally laid down
(deposited) horizontally and can later be deformed.
Law of Original Horizontality
Layers of sediments spread out in all directions until they thin out at the edge of the depositional basin or grade into a different kind of sediment.
Law of Lateral Continuity
In an undisturbed stack of rock layers, the youngest layer is on top, and the oldest is at the bottom. Each layer is younger than the one below it and older than the one
above it.
Law of Superposition
A rock mass that contains pieces of rocks called inclusions are younger than the other rock masses
Law of Inclusion
This states that geologic features that cut across rocks are younger than the rocks which they cut through.
Principle of Cross-Cutting Relationship
is the process of showing that rocks or geologic events occurring at different locations are of the same time age.
CORRELATION
TYPES OF CORRELATION
Physical Correlation
Fossil Correlation
Color, texture and types of minerals
contained within a stratum (layer)
Physical Correlation
- fossils with unique characteristics such
as life span and features - estimate the age of the rocks or rock layer that
contain the fossils
Fossil Correlation
are remains of organisms that lived prior to the last glacial period about 10 000 years ago.
FOSSILS
refers to the study that focuses on
stratified or layered rocks in terms of time and space.
Stratigraphy
is the layering that occurs in most
sedimentary rocks.
Stratification
is the chronology of the Earth’s formation, changes, development, and existence. These events are
measured on a geological time scale.
GEOLOGIC TIME
Scientists do not measure geologic time on a clock or calendar. They use a _________ based on the age of rocks and their corresponding fossils as well as the change in life that occurred over millions of years.
LINEAR TIMELINE
TRUE OR FALSE
Geologists have divided Earth’s history into a series of time
intervals. These time intervals are not equal in length like the
hours in a day. Instead, the time intervals vary in length. This is
because geologic time is divided using significant events in the
history of the Earth.
TRUE
How do geologists come up with geologic time?
They are able to come up with the geologic time scale through absolute dating and relative dating techniques.
How relative and absolute dating were used to determine the
subdivisions of geologic time?
To track down the events that took place in the Earth, geologists and paleontologists had turned their eyes on the rocks. In the 1800’s these scientists don’t know yet the ages of rocks, but one thing is sure they had fully understood relative
ages.
________ enables them to determine the relative ages of rocks based on the stratigraphic principles. In this process, scientists do not determine the exact age of the
rock or the fossils in it. They determine which ones are older or
younger than others.
Relative Dating
older rock layers contain only ____ fossils and younger rock layers may also contain _____ fossils.
reptile
mammal
first step in creating the geologic time scale. It does not only show the order in which life on Earth changed but also how certain areas
changed over time with regards to climate or type of
environment
Ordering rock layers from oldest to youngest
One example of an index fossil is _____. It was found out that trilobites existed during the Paleozoic era from middle
Cambrian period to the Permian period.
trilobite fossil
is a process of correlating rock
layers of different location through the presence or absence of a
certain index fossil.
MATCHING
The age of an unknown fossil could also be determined through the use of
index fossils
had helped in determining geological history. They are able to tell us the relative age of rocks and even the age of unknown fossils
INDEX FOSSILS
is the “calendar” for events in Earth’s history.
GEOLOGIC TIME SCALE (GTS)
The enumeration of those geologic time units is based on
stratigraphy
The index _____ forms that occur in the rocks provide the chief means of establishing a geologic time scale, with the timing of the emergence and disappearance of widespread ______ from the fossil record being used to ______ the
beginnings and endings of each unit of time in the GTS.
fossil
species
delineate
GTS is subdivided into named
units of abstract time arranged in descending order of duration
namely ____, ____, _____, ____, and ____.
eons
eras
periods
epochs
ages
longest period
EONS
shortest period
AGES
is the broadest category of geological time.
EON
oldest to youngest Eons
Hadean,
Archean,
Proterozoic and Phanerozoic.
Hadean,
Archean and Proterozoic or Pre-Cambrian Eon
We live during the _______, which means “visible life”. This is the
interval of geological time characterized by abundant, complex fossilized remains
Phanerozoic
The smaller time interval that divides an EON. It is divided into three: Cenozoic, Mesozoic and Paleozoic. Very significant events in the earth’s history are used to determine the boundaries of the era.
Era
eras are subdivided into units of time called
periods
this is a time where there
is or no known living organism.
Pre-Cambrian Eon
- formation of the solar system and its
planets - formation of early waters in the planet
Hadean
*early bacteria and algae start to exist
*early oxygen was produced by prokaryotic
organisms which led to a build up in the atmosphere
*Oxygen Crisis
Archean
