Textbook Notes (368,164)
Canada (161,688)
York University (12,802)
NATS 1740 (47)

chpteres 7 to 9.doc

6 Pages
Unlock Document

Natural Science
NATS 1740
Randy Hoffman

Chapter 7 Earth and the Terrestrial Worlds 7.1 Earth as a planet  Surfaces of the 5 terrestrial planets all looked similar when they were young  All 5 made of rocky material that condensed in the solar nebula  All 5 were impacted on by objects  Mercury  Covered in craters except in areas with volcanoes  Venus  Covered in thick atmosphere with clouds that hide its surface from view  Has volcanoes  Mars  Has the largest volcano and canyon Why is earth geologically active? - Surface is being constantly changed Interior Structure  Core: highest density material consisting of metals like sickle, iron  Mantle: rocky material of moderate density (mostly minerals)  Crust: lowest density rock such as granite and basalt  Lithosphere: outer layer of cool rigid rock Differentiation and Internal Heat  Differentiation: results in layers made of different materials - Earth and the other terrestrial worlds were once hot enough inside for their interiors to melt, allowing material to settle into layers of differing density Internal heat and geological activity  Convection: process which hot material expands and rises while cooler material contracts and falls - Larger planets retain internal heat much longer than smaller ones and this heat drives geological activity The Magnetic Field - Earth’s magnetic field is generated by the motions of molten metal in its liquid outer core  Magnetosphere: protective bubble that surrounds our planet What processes shape the earths surface?  Impact cratering: excavation of bowl shaped impact craters by asteroids or comets crashing into a planet  Volcanism: eruption of molten rock or lava  Tectonics: disruption of a planets surface by internal stresses  Erosion: wearing down or building up of geological features by wind water ice  Virtually all geological features originate from impact cratering, volcanism, etc. Impact cratering - Travel at 40,000 – 250,000 km/h - Like all terrestrial worlds, earth was hit by impacts when it was young but most ancient craters have been erased by other geological processes Volcanism - Earth’s atmosphere and oceans were made from gases released from the interior by volcanic outgassing  Outgassing: water and gasses are trapped beneath the surface, later erupt releasing some of the gas into the atmosphere - Our atmosphere is 77% Nitrogen Tectonics  Plate tectonics: plates that move under, over and around each other - Tectonics and volcanism generally occur together because both require internal heat and therefore depend on a planets size Erosion - Erosion can both break down and build up geological features - Much bigger role on earth than any other planet How does Earths atmosphere affect the planet? - Our atmosphere is 77% nitrogen and 21% oxygen and rest other gasses Surface protection - Ozone absorbs the suns dangerous ultraviolet radiation while xrays are absorbed by atoms and molecules higher up in the atmosphere - Ozone located in stratosphere The greenhouse effect - Our atmosphere traps additional heat making the earth really warm - The greenhouse effect keeps earths surface much warmer than it would be otherwise allows water to stay liquid over most of the surface - Greenhouse effect only occurs when atmosphere contains gasses that can absorb infrared light  Greenhouse gasses: good at absorbing infrared light  H20 CO2 CH4 7.2 The Moon and Mercury: Geologically Dead Was there ever geological activity on the moon or mercury? Geological feathers of the moon  Lunar maria: smooth/dark regions on the moon - Moon is heavily cratered - The moons dark smooth maria were made by floods of molten lava billions of years ago, when the moons interior was heated by radioactive decay - No longer geologically active Geological features of mercury - Lots of impact craters but less crowded together than moons - No longer has volcanic activity - Caloris basin huge impact crater - Mercury seems to have shrunk long ago leaving long steep cliffs 7.3 Mars: A Victim of Planetary Freez
More Less

Related notes for NATS 1740

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.