ev·o·lu·tion/ˌevəˈlo oSHən/

(noun) the process by which something changes

over time

The Lithosphere

• The lithosphere is the hard outermost shell of our planet on which we live. • In the

mantle below it is molten rock called magma.

Volcanos

Evidence of molten rock below the lithosphere is lava flowing at the surface from volcanos.

Plate Tectonics

The lithosphere floats above the molten rock and it is not one solid sheet but as evidenced by volcanic and seismic activity it is broken into plates.

Boundaries

• The place where 2 plates meet are called boundaries.

• There are 3 types of boundaries:

Divergent Boundaries

• At divergent boundaries the plates are moving away from one another.

• This is happening at the bottom of the oceans creating a deep ocean trench.

• Also referred to as sea-floor spreading.

Convergent Boundaries

There are 2 type of convergent boundaries; these are typically areas of mountain building and uplift.

Transform Boundaries

• Transform boundaries happen where 2 plates are sliding past one another in opposite directions.

• The most classic example of this is the San Andreas Fault line:

The Ring of Fire

• The boundaries of the Pacific Plate are collectively known as the Ring of Fire due to the high amount of volcanic and seismic activity. • The Hawaiian

Islands have been built up from lava flowing from what is called a hot spot which is a sort of weak spot in the lithosphere.

Igneous Rock

• Cooled and hardened lava is called igneous rock.• Depending on the minerals (type of molecules)

contained in the lava and the environment in which it cooled there is a wide variety of different formations of igneous rock such as:

• Lava that cools rapidly (as in in cold water) doesn’t have time to form crystals and becomes a type of black glass which is called obsidian.

• Lava that contains a lot of gases trapped in it becomes very lightweight rock called pumice.

Erosion

Mountains are built and mountains are broken down into smaller and smaller pieces through many types of weathering. When those pieces are moved from one place to another it is called erosion. There are 2 general categories:

PHYSICAL

CHEMICAL

Physical Weathering

The main agents of physical (aka mechanical) are:– Water– Wind– Glaciers– Wedging

Erosion by Water

• As a river flows from the mountains to the sea, the river forms a variety of features including valleys, waterfalls, flood plains, meanders, and oxbow lakes.

• As the river flows down the mountain it picks up sediment, very tiny pieces of chipped off rock.

Erosion by Waves

• The energy in waves comes from wind that blows across the water’s surface. 

• As the wave approaches the shore it makes contact with the bottom shaping and sculpting it with its full force, tumbling (smoothing) rocks and shells caught in its grip.

Erosion by Glaciers

• Glaciers are giant rivers of ice that move ever so slowly across the landscape grinding and polishing and sometimes even picking up rocks and sediment along the way.

• When they melt/recede they can leave gouges in the earth and even giant boulders behind.

Erosion by Wind

• Wind is the weakest agent of erosion and really only effects places where there are no plants to hold down the soil (dunes, deserts).

• Wind moves surface materials around in a process called deflation and it can polish rocks in a process called abrasion (think sand blasting).

Wedging

• As cracks in rocks form, rain can seep down in the cracks and then if the rainwater freezes, it expands, wedging the crack apart wider and wider. This is called frost wedging.

• Plant roots can also act as a wedge to pry apart rocks; we call this root wedging.

Sediment Deposition

• The small pieces of material that come from rocks or plant & animal remains are called sediment.

• After sediment is picked up by various agents of erosion (wind, water, glaciers, waves) it must come back down…and this is part of the process of is called deposition.

Sedimentary Rock

• When layers of sediment accumulate/build up and they stick together over time they become sedimentary rocks.

• Ex: Mudstone, Sandstone, Shale, Conglomerate• This is the type of rock in which one would find

fossils.

Metamorphic Rock

• When igneous and sedimentary rock are exposed to heat and/or pressure chemical changes happen in the rock that transform them into different rocks.

• This type of rock is especially hard and durable.• Examples:

– Marble (parent rock is limestone which is sedimentary)• Used in statuary and as a building material

– gneiss (parent rock is granite which is igneous)– slate (parent rock is shale which is sedimentary)

• Used as old school chalkboards and in pool tables

What is a Rock?

• Rocks are non-living substances made up of minerals.• Minerals are naturally occurring, homogeneous inorganic

solid substances having a definite chemical composition and characteristic crystalline structure, color, and hardness.

The Rock Cycle

• All rock begins its journey around the Earth as magma under the surface. It comes to the surface as lava and cools to form igneous rock.

• Igneous rocks are worn down over time through erosion and deposited in layers before being cemented into sedimentary rock.

• With heat and pressure igneous and sedimentary rocks can change their chemical composition becoming altogether different rocks called metamorphic rocks.

• With additional heat and pressure the rocks melt back into magma and the process begins all over again.

http://www.google.com/url?sa=i&rct=j&q=the+rock+cycle&source=images&cd=&cad=rja&docid=k807PzrHzbhejM&tbnid=1zYXph_mUXiPDM:&ved=0CAUQjRw&url=http://www.learner.org/interactives/rockcycle/&ei=1Ot_Ua2DJIiQ9QST6IDIAw&psig=AFQjCNEG2eXr2a7abKLyjy3PLdN14ZRJxA&ust=1367424334805276

Fossils

• The preserved remains or traces of an organism that lived in the past are called fossils.

• Scientists that study fossils are called paleontologists.• The fossil record provides invaluable information about the

history of life and past environments on Earth, including the climate.

• In many cases the fossil remains are all remains of some extinct species.

• It has been estimated that over 99.9% of all species that ever lived are now extinct (no longer existing).

Types of Fossils

• Fossils are ONLY found in sedimentary rock and there are several different types of fossils such as: Petrification Casts Molds Carbon films Trace fossils Preserved remains

Petrification

• Petrification means “turned into stone.”• This is a process in which all the parts of the organism are

replaced with minerals.

Casts & Molds

• A mold is a hollow area in the shape of an organism.• When that mold fills in with sediment and that sediment

hardens into the shape of the organism, that “copy” is called a cast.

Trace Fossils

• Trace fossils provide evidence of the activities of ancient organisms such as: Footprints which tell paleontologists how they moved,

if they lived alone, etc. Poop – aka coprolite (fancy scientific term for fossilized

poop) Specialized habitats such as nests, burrows or dens.

Carbon Films

• Carbon films are thin sheets of carbon only that are left behind on rock when the other components of the organism decay away.

• Paleontologists that specialize in ancient plants and fish get a lot of information from these as they preserve delicate small fishbones, flowers and leaves very well.

Preserved Remains

• Sometimes entire organisms can be preserved in special conditions where there is an absence of exposure to oxygen such as: Tar pits – thick oil Ice Amber – tree sap

Index FossilsIndex Fossils

Index fossils are particularly helpful in determining the age of a rock layer in the field because they:•Are distributed widespread geographically •Existed for a short range of geologic time•Examples:

<Trilobites lived from about 500 million years ago to 250 million years ago

<Ammonites indicate an age range of about 440 million years ago to 360 million years ago

Dating Techniques

Geologists and archaeologists employ two main dating techniques to determine the age of rocks (or artifacts):

Relative Dating Absolute Dating

Relative Dating

• Relative dating can determine the sequential order in which a series of events occurred, not when (the actual absolute date) they occur.

• Relative dating is done with 3 basic laws of geology in mind:The Law of SuperpositionThe Law of Original HorizontalityThe Law of Crosscutting Relationships

Law of Superposition

The Law of Superposition states that in horizontal sedimentary rocks, the bottom layer is oldest & each layer above it is increasingly younger…

The Law of Original Horizontality

The Law of Original Horizontality states that in general (though there are a very few exceptions) sediment is deposited horizontally.

Law of Crosscutting Relationships

The Law of Crosscutting Relationships states that any rock that cuts across sediment layers is younger than the youngest layer it cuts through.

Unconformity

An unconformity is a place in the rock record where an entire layer of rock has been eroded away creating a gap in the timeline.

Absolute Dating

• Absolute dating uses natural radioactive decay within the rock to establish an actual date.

• Also called radiometric dating.

The AtomThe Atom• Nucleus

– Protons – positive charge – Neutrons – neutral/NO charge

• Orbiting the nucleus – Electrons – negative charge

Atomic StructureAtomic Structure• Atomic number

An element’s identifying number! Number of protons in the atom’s

nucleus

• Mass number Number of protons plus (added

to) the number of neutrons in an atom’s nucleus

Isotope • Variant of the same parent atom • Different number of neutrons

and therefore a different mass number

RadioactivityRadioactivity

Radioactivity is the spontaneous breaking apart (decay) of atomic nuclei

• Parent – an unstable isotope• Daughter products – isotopes formed

from the decay of a parent

Radioactive DecayRadioactive Decay

Types of radioactive decay

• Alpha emission • Beta emission • Electron capture

Radiometric DatingRadiometric Dating• Half-life – the time for one-half of the

radioactive nuclei to decay • Requires a closed system• Cross-checks are used for accuracy • Complex procedure • Yields numerical dates

Decay CurveDecay Curve

Carbon-14Carbon-14

• Half-life of only 5,730 years • Used to date very recent events • Carbon-14 produced in upper

atmosphere • Incorporated into carbon dioxide • Absorbed by living matter

• Useful tool for anthropologists, archaeologists, historians, and geologists who study very recent Earth history

Geologic time scale Geologic time scale

4 billion years is a REALLY long difficult to fathom length of time.

Geologists have divided that history into manageable units.

The timeline was originally created using relative dates but has since been edited using radiometric techniques.

EonEon

•Eons are the largest subdivision of geologic time

•Four eons from oldest to most recent –– Phanerozoic– Proterozoic– Archean– Hadean

ErasEras

• Eons are subdivided into Eras• Eras of the Phanerozoic eon

•Cenozoic (“recent life”)

•Mesozoic (“middle life”)

•Paleozoic (“ancient life”)

PeriodsPeriods

• Eras are subdivided into periods.

• Fossils before the cambrian are rare so all of geologic history before the cambrian is refered to simply as the precambrian.

EpochsEpochs

• Periods are subdivided into epochs.

• We are currently living in the holocene.

Problems with DatingProblems with Dating

• Not all rocks are datable. For instance sedimentary ages are rarely reliable because they are collections of sediment from rocks of differing ages.

• Materials are often used to bracket events and arrive at ages.

The PrecambrianThe Precambrian

The Precambrian is from Earth’s formation 4.6 billion years ago to about 543 million years ago and is characterized by:

– Volcanic eruptions, meteorites, intense radiation from the sun

– Early atmosphere had no oxygen– Prokaryotic organisms (no nucleus)– Cyanobacteria appeared producing their own food

from the sun’s energy from photosynthesis and they created the oxygen atmosphere.

– The Ozone layer forms in the upper atmosphere and absorbs radiation from the sun.

The PaleozoicThe Paleozoic

The Paleozoic spans from 541 to 252.2 million years ago and is characterized by:⁻Rocks rich in fossils of sea creatures such as sponges, corals, clams, squids, and trilobites⁻Fishes appear, sharks are more abundant ⁻Forests of giant ferns covered earth

Gondwanaland

The MesozoicThe Mesozoic

The Mesozoic spans from 252 to 66 million years ago and is characterized by:

– Dinosaurs and other reptiles, referred to as The Age of Reptiles

– First birds appeared; flowering plants appeared– The “birth of the Himalayas.”– Ending in a mass extinction event in which ~75% of non-

avian dinosaurs disappear.– The extinction event is believed to have been caused by a

meteorite impact due to a rock layer from that time (called the K-Pg Boundary) that contains extremely high levels of iridium which is rare on Earth but common in meteors.

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=4vwxaRqQ-UIxRM&tbnid=TjG3Ci9JoDB3QM:&ved=0CAUQjRw&url=http://nexusilluminati.blogspot.com/2010/06/case-against-pangaea-expanding-earth.html&ei=tSCEUcb_JJPo9gTYz4GgCA&psig=AFQjCNHsO0HzRGpF8iS-Vqdx13pwpWBrhA&ust=1367700007880580

The CenozoicThe Cenozoic

The Cenozoic spans from 66 million years ago to the present and is sometimes referred to as the “Age of Mammals”

– Mammals included mastodons, wholly mammoth, saber-toothed cats, camels, and giant ground sloths

– Included some periods of heavy glaciation known as ice ages

– Includes the emergence of man

Natural SelectionNatural Selection

Natural selection is the gradual, non-random process by which biological traits become either more or less common in a population through reproduction.

VariationVariation

The heritable differences that exist in every population that are the basis for natural selection.

OverproductionOverproduction

Organisms produce more offspring than can survive which increases the survival of the species but creates competition for resources.

AdaptationAdaptation

A variation that allows certain offspring a better chance to survive and most importantly to reproduce.

Descent with Descent with ModificationModification

Over time, natural selection will result in species with adaptations that are well suited for survival and reproduction in a given environment.

Evidence for EvolutionEvidence for Evolution

• Adaptations–Structural–Physiological

• Fossils• Anatomy

–Homologous structures–Analogous structures

• Biochemistry

MimicryMimicry

Examples:•Coral snakes (venomous) and king snakes (non-venomous) The harmless king snake mimics the poisonous coral snake, causing would-be-predators to avoid them.•Monarchs (toxic to predators) and viceroys (non-toxic). The viceroys mimics the coloration and pattern of the unpalatable monarch, also avoiding would-be-predators.

CamouflageCamouflage

Camouflage is the use of any combination of coloration or illumination for concealment, either by making them hard to see, or by disguising them as something else.

CamouflageCamouflage

Camouflage is the use of any combination of coloration or illumination for concealment, either by making them hard to see, or by disguising them as something else.

Physiological Physiological AdaptationsAdaptations

Example:

FossilsFossils

Fossils in older layers are more primitive than those in upper layers.

““Missing Links”Missing Links”

Example:Archaeopteryx links reptiles and birds.

Homologous StructuresHomologous Structures

Similarities in the bone structure of the forelimbs of mammals demonstrate evidence for evolution: comparative anatomy and common ancestry.

Analogous StructuresAnalogous Structures

Show similarities in function, but are not evidence of a common ancestor--an example of convergent evolution.

Vestigial StructuresVestigial Structures

Structures that have lost most or all of its ancestral function in a given species but they do indicate common ancestry.Examples:•Whale & snake hip bones•Human appendix•Human tail bone (coccyx)

EmbryologyEmbryology

• The study of the development of an embryo from the fertilization of the ovum to the fetus stage.

• The embryos of fish, reptiles and mammals all have a tail and pharyngeal pouches. In fish, these pouches develop into the supports for the gills, while in the mammals and reptiles (birds too), they develop into parts of ears, jaws, and throat.

• These shared features in young embryos suggest evolution from a distant, common ancestor.

BiochemistryBiochemistry

• 95% of all life on Earth is made of just 6 elements: CHNOPS.

• Cells of all living organisms contain DNA with the same 4 base nucleotides.

• All living organisms produce ATP for energy.

• Similarities in DNA sequences can be used to show common ancestry; the more similarities, the more recently evolved the species are from one another.