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- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/02%3A_The_Origin_of_Earth_and_the_Solar_System/2.06%3A_Chapter_2_Summary_and_Key_Term_CheckMaterial drawn to the centre forms a star, and the remainder forms a disk around the star. Heating caused molten metal to sink to Earth’s centre and form a core, and silicate minerals to form the mant...Material drawn to the centre forms a star, and the remainder forms a disk around the star. Heating caused molten metal to sink to Earth’s centre and form a core, and silicate minerals to form the mantle and crust. A collision with a planet the size of Mars knocked debris into orbit around Earth, and the debris coalesced into the moon. The search for exoplanets has identified 60 planets that are similar in size to Earth and within the habitable zone of their stars.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/17%3A_Mass_Wasting/17.01%3A_Factors_That_Control_Slope_StabilityWe can split the vertical gravitational force into two components (vectors) relative to the slope: one pulling the block down parallel to the slope (the shear force), and the other pulling the block d...We can split the vertical gravitational force into two components (vectors) relative to the slope: one pulling the block down parallel to the slope (the shear force), and the other pulling the block directly into (i.e., perpendicular) to the slope (the normal force). The shear force pulls the block down the slope, but the block doesn’t move unless the shear force overcomes the strength of the bond between the block and the slope.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/17%3A_Mass_Wasting/17.04%3A_Chapter_15_Summary_and_Key_Term_CheckSlope stability is controlled by the slope angle and the strength of the material on the slope. The key criteria for classifying mass wasting are the nature of the movement that takes place, the type ...Slope stability is controlled by the slope angle and the strength of the material on the slope. The key criteria for classifying mass wasting are the nature of the movement that takes place, the type of material, and the speed of the material movement. Mass wasting events can be a precipitous fall of rock through the air, material sliding as a solid mass along either a plane or a curved surface, or internal flow of material as a viscous fluid.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/12%3A_Volcanism/12.01%3A_What_Is_A_VolcanoThe loss of support causes part of the volcano to collapse into the void in the magma chamber, leaving behind a broad basin rimmed by the remnants of the volcano. The caldera formed after an enormous ...The loss of support causes part of the volcano to collapse into the void in the magma chamber, leaving behind a broad basin rimmed by the remnants of the volcano. The caldera formed after an enormous eruption between 1627 and 1600 BCE [1] . The eruption is thought to have contributed to the downfall of the Minoan civilization, and some speculate that it might also be the source of the myth of Atlantis, a story about a lost continent that sank beneath the sea after a natural disaster.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/12%3A_Volcanism/12.08%3A_Volcanoes_in_CanadaThe North American Plate is moving in a westerly direction at about 2 cm per year with respect to this plume, and the series of now partly eroded shield volcanoes between Nazco and the coast is interp...The North American Plate is moving in a westerly direction at about 2 cm per year with respect to this plume, and the series of now partly eroded shield volcanoes between Nazco and the coast is interpreted to have been formed by the plume as the continent moved over it.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/11%3A_Measuring_Geological_Time
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/21%3A_Earth-System_Change/21.05%3A_Humans_in_the_Earth_SystemFor most of the past 1000 years, the atmosphere has had a δ 13 C of approximately -6.5‰. The carbon-isotope composition of organic matter is much lower than that of the atmosphere, so the mixing in of...For most of the past 1000 years, the atmosphere has had a δ 13 C of approximately -6.5‰. The carbon-isotope composition of organic matter is much lower than that of the atmosphere, so the mixing in of carbon from fossil fuels causes the over-all carbon-isotope composition of the atmosphere to decrease.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/01%3A_Introduction_to_Geology/1.04%3A_We_Study_Earth_Using_the_Scientific_MethodSaying that an idea is a hypothesis is like suggesting, “Maybe the world works this way.” Saying that an idea is a theory is like concluding, “It’s extremely unlikely that the world works in a way oth...Saying that an idea is a hypothesis is like suggesting, “Maybe the world works this way.” Saying that an idea is a theory is like concluding, “It’s extremely unlikely that the world works in a way other than this.” If our experiment didn’t specifically check for the mechanism (e.g., by looking to see if chips fall off the rocks and the rocks are made smoother) then we would have to acknowledge the possibility.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/01%3A_Introduction_to_Geology/1.05%3A_Three_Big_Ideas-_Geological_Time_Uniformitarianism_and_Plate_TectonicsArguably, saying that “the present is the key to the past” is an oversimplification on Lyell’s part isn’t exactly fair to Lyell, given his phrasing about the “permanency of the laws of nature.” (Autho...Arguably, saying that “the present is the key to the past” is an oversimplification on Lyell’s part isn’t exactly fair to Lyell, given his phrasing about the “permanency of the laws of nature.” (Author’s note: I have been unable to find that exact “key to the past” quote so far, so at this point we have to allow for the possibility that Lyell didn’t oversimplify at all, and he’s getting in trouble for what someone else said.
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/04%3A_Minerals
- https://geo.libretexts.org/Courses/Sierra_College/Physical_Geology_(Sierra_College_Edition)/08%3A_Sedimentary_Rocks/8.06%3A_Groups_Formations_and_MembersA formation is a series of beds that is distinct from other beds above and below, and is thick enough to be shown on the geological maps that are widely used within the area in question. A series of f...A formation is a series of beds that is distinct from other beds above and below, and is thick enough to be shown on the geological maps that are widely used within the area in question. A series of formations can be classified together to define a group, which could be as much as a few thousand metres thick, and represents a series of rocks that were deposited within a single basin (or a series of related and adjacent basins) over millions to tens of millions of years.
