3.5: Chapter Summary
- Page ID
- 28679
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)3.1 Earth's Interior
- Earth's interior can be described both by its composition and its physical properties.
- Earth's compositional layers include the crust (both continental and oceanic), the mantle, and the core.
- Continental crust is, on average, granitic in composition; oceanic crust is, on average, basaltic.
- Earth's mantle is made of ultramafic minerals.
- The core, though it has not been observed directly, is believed to be made of iron and nickle alloys.
- Mechanically, Earth can be divided into the rigid lithosphere, the flowing asthenosphere, the lower mantle (or mesosphere), the liquid outer core, and the solid inner core.
3.2 Tectonic Plates, Plate Motion, and Plate Boundaries
- The Earth's surface is made up of tectonic plates that are constantly moving. There are three types of plate boundaries: divergent, convergent, and transform.
- Divergent boundaries are where plates move apart. This creates new crust as magma rises from the mantle.
- Convergent boundaries are where plates move together. This can cause subduction, where one plate is pushed under the other, or collision, where the plates grind together.
- Transform boundaries are where plates slide past each other.
- The movement of tectonic plates is responsible for many of the Earth's features, such as mountains, oceans, volcanoes, and earthquakes. It is also thought to be responsible for the formation of supercontinents.
3.3 Mechanisms for Plate Motion
- While convection is believed to be part of reason for tectonic plate motion on Earth, it is driven by two other processes: ridge push and slab pull.
- Ridge push is the process by which boyant new crust forming at mid-ocean ridges apply a force on neighboring lithosphere.
- Slab pull is the result of old, cold oceanic crust subducting and pulling on the lithsphere behind it.
3.4 California's Plate Boundaries
- California is home to all three types of plate boundary types.
- Most famously is California's San Andreas fault system, which is a transform boundary between the North American plate and the Pacific plate.
- Lesser known, but more likely to produce large earthquakes is the Mendocino transform fault off the coast of California where the Pacific and Juan de Fuca/Gorda plates are sliding past one another.
- North of the Mendocino triple junction, convergence in the form of subduction is taking place. The Juan de Fuca/Gorda plate is subducting beneath the North American plate.
- In the Gulf of California, Baja California is actively rifting away from mainland Mexico, forming our very own divergent boundary.