History of the Earth

theory that Earth's rock layers formed in a global flood followed by the uplifting of rocks and mountain building over a short, violent period, possibly in the recent past

theory that rocks form slowly over time through processes of volcanism, erosion, and sedimentation

a technique for estimating the age of species by comparing molecular differences between species

dirt, pieces of rock, and the remains of living things at the bottom of oceans, seas, and lakes

geologic principle that Earth's processes act in the same manner today as they always have throughout Earth's history

The fossil record Comparative anatomy Molecular clocks

Gradual processes of rock formation The fossil record Radioactive dating

The movement of galaxies Chemical composition of the Sun

4.6 Billion Years Old

a fossil that is widespread geographically but only occurs in one layer or a small number of layers of rock

in a sequence of layered rocks, the crosscut, or intrusive feature, is younger than the layers it intercedes

animals and plant fossils occur in consistent sequences through time, generally changing from simpler to more complex

sediment deposited into water will settle at the bottom in flat, horizontal layers

sediment deposited into water will spread in a horizontal and continuous sheet, unless it runs out of sedimentary material, or it hits a barrier

any undisturbed sequence of layered rocks has the oldest rock on the bottom and newest rock on the top

study of fossils

process to determine the general time sequence of historic events, rock strata, and fossils

study of rock layers and the processes that form them

geologic time measured in a specific duration of years

a technique for estimating the age of species by comparing molecular differences between species

spontaneous disintegration of the atoms of certain isotopes into new isotopes

dating a rock or mineral by measuring the proportions of an original radioactive material and its decay products

placing events in chronological order without reference to their ages measured in years

the time it takes for half of the atoms of an element to change from parent to daughter atoms

some biologists question whether rates of change in biological molecules are constant enough to use molecular clocks to measure how long ago changes in species occurred

constant and unique

the rate at which radioactive decay occurs how much radioactive decay has occurred

absolute time

relative time

longest interval of geologic time

major divisions of geologic time within each eon; identified by major changes in the fossil record

a cell that has complex internal structures, such as a nucleus; e.g., plant and animal cells

major divisions of geologic time within each era; identified by changes in the fossil record

a simple cell that lacks complex internal structures, e.g., bacterial cells

fossil mounds made of ancient photosynthetic bacteria, flourished during Archean

4.5 to 3.8 billion years ago not a geologic time interval, no rocks asteroids and large meteorites were still bombarding the new planets release of heat from these collisons made the Earth molten at this time formation of the color system

3.8 to 2.5 Billion Years Ago began when the surface of the Earth was cooled full of poisonous gases; methane, ammonia, and other toxic gases from volcanic activity first fossils began (3.5 billion years ago), ancient bacteria

prokaryotic

Western Australia

2.5 Billion to 543 Million Years Ago first fossils of eukaryotic cells stable continents formed oxygen build up from photosynthetic bacteria such as stromatolites explosion of multicellular life forms, especially plants towards end, first simple animals

compete with other organisms

543 Million Years Ago to the Present first appearance of hard-shelled animals evolution of bony fish and all forms of land plants and animals divided into eras; Paleozoic, Mesozoic, and Cenozoic

Significant changes in the fossil record

543 to 248 Million Years Ago 1. an "explosion" of new life begins with Cambrian explosion small, shelled animals, such as trilobites, brachiopods, mollusks, and different types of corals ruled the ocean land plants grew rapidly Animals with bones—vertebrates—came next. 2. the largest mass extinction killed off almost 90% of all marine animal species still debating its cause

248 to 65 Million Years Ago means middle animals dinosaurs dominate Divided into: Triassic - dinosaurs first appeared, Jurassic - diverse dinosaurs Cretaceous ended with mass extinction, ended by a meteor, all dinosaurs and certain land animals, small mammals and birds lived

65 Million Years to the Present age of mammals misnamed because birds, insects, and flowering plants also dominate it

common gray to black volcanic rock, usually fine-grained due to rapid cooling of lava

the advance and retreat of large masses of slow-moving ice

the process in which huge numbers of species die out suddenly

process by which the earth's crust is pulled apart and new crust forms

the disasters come either from above, in the form of deadly asteroids or comets, or from below, in the form of extreme volcanic activity

Phanerozoic Eon

440 million years ago earliest extinction in history second largest extinction in history associated with a period of glaciation (the formation and retreat of glaciers) before, shallow, warm, continental seas were the perfect environment for many groups of organisms 60% of marine species was lost glaciation affected tropics

climatic cooling major glaciation sea level drop

tropical animals such as bryozoans and brachiopods (half were gone)

364 million years ago about 20% of all animal families and 70-80% of all animal species were lost profound changes in oceanology from loss of tabulate corals and stromatoporoids

asteroids hitting the earth the growth of forests climatic changes sea level changes

The growth of forests that led to environmental changes and subsequent cooling.

conodonts jawless fish rugose and tabulate corals stromatoporoid sponges trilobites

251 million years ago worst mass extinction 95% of all species on planet 70% of all land species, such as plants, insects, and vertebrate animals 96% of the planet's marine species lost many scientists suspect a comet or asteroid impact (no evidence or crater to prove that) massive volcanism from the Siberian Traps and a related loss of oxygen in the seas

an asteroid impact triggered massive volcanism

asteroid hitting the earth massive volcanism producing climate change and related loss of oxygen in the seas combination of an asteroid and volcanism

199 million to 214 million years ago 58 cephalopod families disappeared killed 52 percent of marine species occurred in a series of stages conodonts extinct Only 11 of 50 reef organisms survived

rifting of the earth global warming

a.k.a the K-T extinction 65 million years ago killed off the dinosaurs an asteroid impact - created the Chicxulub crater at the tip of Mexico's Yucatán Peninsula dinosaurs, pterosaurs, plesiosaurs, mosasaurs, ammonites, and some families of birds and marsupial mammals half the plankton groups, many families of teleost (bony) fishes, bivalves, snails, sponges, sea urchins, and others

created the Chicxulub crater at the tip of Mexico's Yucatán Peninsula caused huge fires, tsunamis, severe storms with high winds, highly acidic rain, seismic activity, and perhaps even volcanic activity

an asteroid hitting the earth volcanism

the gaseous envelope of a planet

long-term weather patterns of a particular area

warming of the atmosphere caused by gases that absorb heat from Earth's surface

to lose gases into the atmosphere

supercontinent which connected the landmasses of the southern and northern hemispheres interior was extremely hot and dry majority of the land was nowhere near the ocean and had very little rainfall

nitrogen (78%), oxygen (21%), and other gases (1%)

early atmosphere

poisonous mostly carbon dioxide hot

protect us by filtering out deadly cosmic rays helps protect us from meteors on a collision course with Earth a role in sustaining life

oxygen

cyanobacteria using photosynthesis

1. cyanobacteria pumped oxygen into the atmosphere 2. oxygen reacted with dissolved iron 3. after reducing the dissolved iron, the oxygen was released into the atmosphere 4. oxygen formed ozone in the upper atmosphere, which shielded Earth from tissue-damaging ultraviolet light

examining the rock record around the world examining ice in Antarctica

volcanism meteor impacts

small changes in Earth's orbit, known as Milankovitch cycles

Earth's orbit changes from more circular to more elliptical and back again these orbital changes take Earth nearer and further from the Sun, which would affect the amount of energy reaching Earth

fluctuated between hot and cold

one large landmass supercontinent interior was extremely hot and dry majority of the land was nowhere near the ocean and had very little rainfall

erupting volcanoes spewed gases, including carbon dioxide, into the atmosphere, carbon dioxide traps heat inside (Greenhouse effect)

slows the metabolism of some creatures loss of many coal swamps amphibians and some spore-bearing plants became extinct

burning fossil fuels that are releasing greenhouse gases

80% of the large mammals in North America went extinct vanishing habitats (extinction of species)

the combination of paleontology and stratigraphy