History of Life Flashcards
What is relative dating?
a method used to establish whether a rock or geological event is older or younger than another without determining its exact age in years.
Relative Dating Principles:
the study of layered sedimentary rocks.
Stratigraphy
Relative Dating Principles:
undisturbed sequence of sedimentary strata, or rock layers, the layers on the bottom are the oldest, and layers above them are younger.
Principle of Superposition:
Relative Dating Principles:
Rock layers, like sediments and lava flows, are initially deposited in a horizontal manner, except at basin edges, where they may tilt slightly downward.
Principle of Original Horizontality
Relative Dating Principles:
Strata in a depositional basin extend continuously until they thin out at the edges or meet a barrier like a ridge. They may also end when deposition extends too far from its source. If a canyon cuts through, the strata remain continuous on both sides.
Principle of Lateral Continuity
Relative Dating Principles:
Deformation events like folds, faults and igneous intrusions that cut across rocks are younger than the rocks they cut across.
Principle of Cross-Cutting Relationships
When one rock formation contains pieces or inclusions of another rock, the included rock is older than the host rock
Principle of Inclusions
Relative Dating Principles:
Fossil groups are unique to their time period and help link rock layers of the same age across different regions, aligning with the geologic time scale.
Principle of Fossil Succession
These occur when rock layers are disrupted, such as sedimentary rock being deposited over igneous or metamorphic rock.
UNCONFORMITIES
types of unconformity:
where is a break or stratigraphic absence between strata in an otherwise parallel sequence of strata.
Disconformity
types of unconformity:
where sedimentary strata are deposited on crystalline (igneous or metamorphic) rocks.
Nonconformity
types of unconformity:
where sedimentary strata are deposited on a terrain developed on sedimentary strata that have been deformed by tilting, folding, and/or faulting. so that they are no longer horizontal.
Angular unconformity
also known as numerical dating, is a method used in geology, archaeology, and other scientific fields to determine the numerical age of rocks, fossils, or artifacts. It provides a specific age range, often expressed in years before the present (BP), years ago (ya), or using calendar dates.
Absolute dating
These are variations of a chemical element that share the same number of protons in their atomic nuclei but differ in the number of neutrons.
isotopes
A technique used to determine the age of materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.
Radiometric dating
a science of dating tree rings to determine the age of wood and the climate in which the tree grew. It’s also known as tree-ring dating.
Dendrochronology
a method used to determine the age of materials by measuring the amount of radiation they have absorbed since their last exposure to sunlight or heat, useful for dating sediments, ceramics, and other materials.
Luminescence dating
Types of Luminescence Dating:
This method involves heating the sample and measuring the light emitted as the trapped energy is released.
Thermoluminescence (TL)
Types of Luminescence Dating:
This method uses light to stimulate the release of trapped energy.
Optically Stimulated Luminescence (OSL)
a system for organizing the history of the Earth into units of time, from the smallest to the largest, based on the events and processes that have occurred.
Geologic Time Scale
the earliest and longest time period in Earth’s history. During this time, planet Earth was formed, the earliest geological events took place, and life on the planet originated.
PRECAMBRIAN TIME
Precambrian Eon subdivisions
Hadean Eon
Archean Eon
Proterozoic Eon
was a period of major evolutionary change. Life diversified from simple marine organisms to complex vertebrates, and the first land animals appeared. The era ended with the largest mass extinction in Earth’s history.
Paleozoic Era
often referred to as the “Age of Reptiles,” spanned approximately 252 to 66 million years ago. It is divided into three periods: the Triassic, Jurassic, and Cretaceous.
Mesozoic Era
the most recent geological era, beginning approximately 66 million years ago and continuing to the present day. Often referred to as the “Age of Mammals,” this era is characterized by the diversification and dominance of mammals, birds, and flowering plants.
CENOZOIC ERA
