Geologic Time Scale
- Geologic time is broken up into eons, eras, periods and epochs in increasingly smaller time units.
- Each segment is divided based on the predominant __________ living in that time period.
- Famous eras include the Paleozoic (age of _______), Mesozoic (age of ________) and Cenozoic (age of _________).
- Mass extinctions punctuate the ends of each era.
- The largest extinction (90% of all life) was at the end of the Permian period and the Paleozoic era.
- The dinosaurs died in a mass extinction at the end of the Mesozoic era.
- Some people believe we are moving into a new era right now and don't realize it...
- Anthropocene- the age of ______: the newest geologic epoch.
- Core: interior of the earth, composed of hot metal (mostly _________),
_________ center, semi fluid outer. Inner core is solid at 6,000 degrees C!
- Mantel: surrounds core, much less dense, composed of light and heavy
elements (Si, _____, and Mg). The mantel is mostly solid but there is one region known as the asthenosphere that is somewhat soft like silly puddy.
- Crust: cool, lightweight ________ rock that "floats" on the denser mantle
- Oceanic crust is dense and thin _________-rich rock.
- Continental crust
is thicker, lighter granite-rich crust
- Originally called Continental __________ .
- Plates were once all connected in a single land mass called ______________
- Tectonic Plates: large pieces of solid land (lithosphere: crust and upper solid mantle) are broken and moved by extreme heat in the soft layer of the mantle (asthenosphere).
- Mapping major earthquakes and _____________ throughout time indicates plate boundaries
Divergent plate boundaries- when plates _____________.
- Magma that gets pushed up from the mantle through
cracks in the oceanic crust pile underwater to create ocean
_________. Huge underwater ___________ are formed, greater than anything
on the continents. ex. Mid-ocean ridge
- Divergent boundaries can occur on land too causing a _______ valley ex. Kenya, Africa
Convergent plate boundaries- when plates __________
- land-land collisions- non-volcanic mountain ranges are pushed up. ex. _____________ Mtns.
- ocean-land collisions- denser ocean plate moves _____________ the less dense continental rock(called a subduction zone) forming volcanic mountain chains and deep ocean trenches. ex. ___________ Mtns.
- ocean-ocean collisions- one of the ocean plates are subducted causing a chain of volcanic islands ex. ____________ or Indonesia. NOT Hawaii- it is caused by a hot ___________: a single plume of pulsing magma creates an island chain as the plates move over it.
Transform plate boundaries- when plates _______ past each other
- Sometimes rocks along faults will become stuck. Pressure can build until the ground suddenly snaps! The __________ is where the earthquake started. The epicenter is the surface location directly above the focus.
- The amplitude of an earthquake's shake is measured by a seismograph. The Richter scale represents the strength of the quake from 1 to 10. Each number is 32 x stronger than the previous but the amplitude of the seismograph is ______x higher.
- Dec. 26, 2004 an earthquake off of Indonesia measuring 9.3 on the Richter scale created a ___________ that killed over 200,000 people.
- Poorly built homes, overcrowding and alteration of the coastal ecosystem also added to the destruction.
- 1883 Indonesian volcano Krakatoa created a tsunami that killed
- An offshore earthquake in 2011 caused a 33 ft high tsunami that hit Japan and caused the meltdown of three Fukushima nuclear power plants. It is still emitting radioactive material today.
- Why could two different earthquakes of the same Richter scale measurement create such vastly different levels of damage?
- Eruptions have created much of the Earth's crust (igneous!) and makes great soil for crops.
- 95% of the volcanoes are found at subduction zones and mid-ocean ridges. The remaining 5% are on _____ ________.
- Volcanoes can destroy lives
- toxic gas- denser-than-air mixtures of
hot gases that move faster than 100 km/hour
- lava flows
- mudslides and tsunamis
- Volcanoes can alter surface temperature
- 1815 was the year without summer. Mt. Tambora, Indonesia spewed out so much ash and sulfur that the Sun's rays were blocked. Just north of us in New Lebanon, NY the temperatures were below freezing every day in May and the ground was frozen solid on June 9.
- In 1991 Mt. Pinatubo in the Phillippines erupted and caused the Earth to cool over 2 degrees F.
What causes the seasons on the Earth?
- The seasons of the Earth are caused by the revolution of the
Earth around the Sun on an angular, _______ degree tilt.
- The hours of __________ to vary.
- The intensity of sunlight to change. The ________ the sun gets in the sky, the more concentrated the sunlight and the more intense the solar radiation.
- When the Northern Hemisphere is experiencing a season, the _________________ season is occurring in the Southern Hemisphere!
- When the
North Pole is tilted 23 1/2 degrees toward the sun, we experience ___________.
- The sun is directly overhead at the Tropic of ____________, 23.5 degrees N.
- The sun's rays become more concentrated on the Northern Hemisphere
because the sun is higher in the sky resulting in __________ temperatures.
- In New Paltz, there are double the hours of ___________ than winter!
- When the South Pole is tilted toward the _______, we experience winter.
- The sun is directly overhead at the Tropic of _____________, 23.5 degrees S.
- The sun's rays are much lower in the sky resulting in __________ temperatures.
- A day only lasts 1/2 as long in __________ as it does in summer!
- When we are experiencing winter we are actually closer to the sun by 3 __________ miles so clearly seasons are NOT caused by distance to the sun!!!
SPRING AND FALL
- At solar noon the sun's rays hit the ___________, 0 degrees latitude, causing everywhere on Earth to have 12 hours of day and 12 hours of night!
The ________ cycle is a model of how all rocks can be formed, transformed, destroyed and reformed depending on the environment and processes that affect them. A rock can transform into any other rock without following a particular _____________ .
The texture of a rock and its mineralogy is the best way to determine its origin:
1. ________________ rocks are made three different ways:
- Clastic rocks are composed of sediments (rock fragments) from weathered rocks. Most of the time these sediments are readily visible and you can see how they are __________________ together. ex. Sandstone and conglomerate.
- Fossils only form in sedimentary rock.
2. _______________ rocks form when magma or lava cools.
- In most cases you can SEE the coarse intergrown crystals (like puzzle pieces). ex. Granite and gabbro
- Rapid cooling, however, can make the crystals so small that you can't see them (fine texture). ex. Basalt and rhyolite
3. Metamorphic rocks are preexisting rocks that have been modified by heat and pressure. These rocks often hold the most economically important minerals such as talc, graphite and gemstones.
- Rocks containing intergrown crystals may show layering, banding or foliation (the layered _____________ of flat crystals). Often the layers look bent or distorted. ex. Schist and gneiss.
- Non-foliated rocks show no evidence of layering. ex. Quartzite and marble.
SOIL: A RENEWABLE RESOURCE... ideally
- mixture of weathered minerals from rocks, decaying organic material,
________ organisms and a dash of _____ and water
- takes ________ years to develop 1 inch of soil from the parent rock!!!! But that time frame can be influenced by __________ (hot and wet speeds things up), living ______________ (the more the merrier), and topography- big slope baaaaad.
- sandy soil: light soil, good ________, dries quickly which leaves most plants thirsty.
- clay (tiny
particles), heavy, impermeable, holds _______ longer which makes soil waterlogged.
- Humus: a sticky, brown residue from decaying plants & animals,
gives structure to soil and helps ___________
- Humus contains millions of organisms- mostly _____________ (bacteria,
algae, fungi) but also worms, insects, animals.
- Loam: perfect agricultural soil with ________ portions of sand, silt, clay and humus.
Soil horizons: layers of soil, reveal the _________, classified
by color, texture, composition
Soil profiles- a cross section through soil horizons
- O horizon (surface litter): newly deposited leaves and partially decomposed organic matter.
- A horizon (top soil): inorganic minerals mixed with ________, where most plants spread their
roots to absorb nutrients
- E horizon (leaching zone): minerals are dissolved in water and carried downwards
- B horizon (sub-soil): dense with clay, nutrients (soluble) and ________ sediments. Leached material is illuviated (deposited).
- C horizon: broken down ____________. Time and further weathering allows
soil to extend downward
- Bedrock- soil parent rock 1/2 of cropland is being destroyed quicker than replaced
Soil erosion is caused by water and _______ in areas that are deforested and/or suffering from poor agricultural techniques (monoculture, overgrazing and planting on slopes).
Soil erosion strips the land of _________ causing more water run off and more soil erosion.
3 Types of Soil Erosion
- __________- huge segments of soil is removed horizontally
- Rill- _______ channels of erosion cut into the land
- Gully- _______ channels of erosion cut into the land
1/2 of cropland is being destroyed quicker than replaced
Soil erosion also fills canals, dams and other _______________ zones.
Water with a lot of suspended soil in it makes salmon reproduction tough, lowers the oxygen levels and changes water pH.
Other issues related to soil erosion include:
- Desertification- deforestation causes deserts to _____________ causing erosion to increase even more.
- Salinization- salty water makes _________ soil and is the worst for plants. Adding fresh water is the best hope.
- Waterlogging- most plants hate to have soggy roots for too long. Drain the soil with pipes or move your crops to _________ ground.
Soil Conservation practices include:
- Keeping ____________ matter on the soil (plant residue, animal manure and compost work well)
- Slow down the effect of ________ using trees and shrubs
- Organic agriculture (yay!) including crop rotation and using animal __________ as fertilizers
- Contour plowing and strip planting to slow down the movement of _________ downhill.