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GEO 102: EXAM TWO
Eon |
unit of time equal to 1 billion years
|
era |
a subdivision of an eon
|
period |
a length or portion of time
|
(etymology)
Phanerozoic
|
"age of animals"
|
(etymology)
Precambrian
|
the age before animals
|
(etymology)
Cenozoic
|
recent animals
|
(etymology)
Mesozoic
|
middle animals
|
(etymology)
Paleozoic
|
ancient animals
|
(etymology)
Proterozoic
|
earlier life
|
(etymology)
Archean
|
beginning or origin (land/oceans/life)
|
(etymology)
Hadean
|
named after Hades, due to Hellish conditions on Earth at the time
|
geologic map
|
shows the geologic age of surface rocks
|
'Strata'
|
layers of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers
|
Stratigraphy |
the branch of geology that studies the composition, origin, age, relationships, and geographic extent of strata
|
Principle of Horizontality
|
(STENO, 1669)
layers of sediment are originally deposited horizontally under the actions of gravity
|
Superposition |
(STENO)
sedimentary layers are deposited in a time sequence, with the oldest on the bottom and youngest on the top
|
Uniformitarianism
|
(HUTTON)
believed in a weathering pattern of rocks, also in sedimentation rate
|
Uniformitarianism
|
(LYELL)
believed in a gradual change-slow process of erosion, proposed idea of rock cycle in 1880's
|
lithostratigraphy
|
using different types of rocks
(absolute age)
|
chronostratigraphy
|
using the different ages of rocks
(relative age)
|
biostratigraphy
|
using different fossil assemblages from rocks
(relative age)
|
lithostratigraphy (definition)
|
rocks defined and organized by their observable physical features
can be sedimentary, igneous or metamorphic rock
|
chronostratigraphy
|
studies the absolute age of rock strata
|
radio active decay (radiometric)
|
changing of atomic mass (weight) of radioactive elements over a certain period of time
|
paleomagnetism (paleomag)
|
the study of the earth's record of the earth'a magnetic field in igneous, and some sedimentary rock
|
Radioactivity |
changing in atomic mass
radioactive elements have high atomic #'s
half life, is the duration of the decay
|
Paleomag
|
polar wondering- paleomag of ancient rocks shows orientations different from present magnetic field
magnetic record in rocks through time
sources of iron bearing minerals
|
Arthur Holmes
|
(1890-1965) pioneer of geochronology; first established Uranium-Lead dating
|
Harry H. Hess
|
(1906-1969)
pioneer of paleomagnetism
|
paleontology
|
the study of creatures/organisms/life in the past
|
what do paleontologists study?
|
fossils
rocks
living organisms
|
fossil |
any remains of an organism from the past
|
'fossus'
|
latin, meaning dug up
|
body fossils
|
shells, skeletons, bomes, skins, feathers, eggs, etc.
|
trace fossils
|
nests, burrows, trackways, coprolites
|
Why is paleontology important?
|
origins of life
evolution
extinction
age of rocks & earth
paleoecology
fossilization
energy sources
|
ammonites |
are the extinct group of cephalopods in mollusks; very common in the mesozoic
|
ammonites |
the study of the process of living things into fossils
|
William 'Strata' Smith
|
(1769-1839)
established the ideas of biostratigraphy through faunal succession
|
faunal succession
|
rocks characterized by a unique set of fossil taxa
a group of fossils (fauna) representing diversity in time
the occurrence of many fossils, possibly restricted in the rock unit
|
biostratigraphy
|
the study and categorization of rock strata based on their fossil content and distribution
defined by first and last appearance of index fossils & fossil assemblages
|
index fossils
|
very common
geographically widespread
easily preserved
diagnosable for species
found in multiple environments
short species duration
(ammonites)
|
evolution |
'change through time'
a process of change in a certain direction
|
Thomas Malthus
|
(1766-1834) first coined the term evolution
studied how a population changed over time
|
biological evolution
|
descent with modification
branching of speciation
change with genetic inheritance
(fossil fish species show descent w modification)
|
morphology
|
changes in the forms and structures, including internal and external body ( head, legs, skeleton, skull, tissues, cells, molecules, DNA)
|
Microevolution |
changes on a small scales within a single population
|
macro evolution
|
groups larger than an individual species
|
gradualism
|
changing consistently through time
|
stasis |
changes not evident or very weak through time
|
Lamarck's theory of evolution
|
(1744-1829) the theory of inheritance of acquired characteristics "use vs. disuse"
|
"Evolution is a fact but not a theory"
|
... |
Origin of species
|
(DARWIN)
1859, 1872
variation (among individuals)
blending inheritance of traits
geographical isolation (of populations)
earth's age & fossils
|
Natural Selection
|
Variation in traits
Differential reporduction
Heredity
End Result
VARIATION + DIFFERENTIAL REPRODUCTION + HEREDITY = NATURAL SELECTION
|
Neo-Darwinism
|
Mutations
Gene flow
Sex
|
Precambrian shield
|
large tracts of exposed metamorphic rocks in the continental interiors, some of the oldest crustal rocks
|
Platforms |
more shield buried under sedimentary rocks
|
Cratons |
collective body of platfoms and shields
|
What can precambrian shields tell us?
|
the origin of the continents
origin of the oceans
the early earth's atmosphere
|
Hadean Eon
|
(4.6-4.0 BYA)
Meteors
Differentiation
First crust formed
|
Archean Eon
|
(4.0-2.5 BYA)
Little volcanic islands smashed together along subduction zones making protocontinents
|
Archean Eon
|
layers of chert and oxidized-iron rich minerals, indicating large presence of oxygen in earth's atmosphere
2.5-2.0 BYA
|
orogeny
|
the formation of mountains, usually accompanied by igneous activity, metamorphism, and crustal thickening
|
"Rodinia"
|
first super-continent
1.3-1.0 BYA
|
what constitutes life?
|
chemically distinct entity that interacts with its surroundings to derive energy, and is capable of self replication
|
life
|
has cells, which come from preexisting cells capable of adaptation, reproduction and death
|
what are the conditions necessary for life?
|
liquid water
chemical elements
sources of energy
sustainable environmental conditions
|
what are the conditions necessary for life?
|
prokaryotic cell, no nucleus membrane, simple structure
produced the major component of the earth's oxygen during the precambrian
|
stromatolites |
most common fossils (2.0-.75 BYA)
a mounded structure built up over long periods of time by layers of cyanobacteria that trapped sediments
photosynthetic organism producing O2
|
eukaryotic cell
|
membrane for nucleus
multiple organelles
complex
|
prokaryotic cell
|
no membrane for nucleus
small
simple structure, no organelles
|
metazoans (animals)
|
multicellular
heterotrophic
terrestrial and aquatic
mostly sexual
|
Ediacaran biota
|
assemblage of first multicellular organisms
fossils that exhibit only molds (impressions) of body parts or tracks, but no actual body remains
600-542 MYA
|
Ediacaran fauna
|
early definitive animals
large (huge) body size
no hard tissues/skeleton
no direct link to living and cambrian animals
|
Geologic map
|
shows the age of surface rocks
|
Precambrian is an
|
eon
|
Stratigraphy
|
study of rock types, age of rocks, rock distribution
|
da Vinci
|
earliest interpretor of fossils
|