Radius 6000 km Mass of the earth 6x1024 kg Density of the earth 552gcc Density

Radius 6000 km mass of the earth 6x1024 kg density of

This preview shows page 8 - 11 out of 36 pages.

- Radius = 6000 km - Mass of the earth = 6x10^24 kg - Density of the earth = 5.52g/cc - Density of rock at the earth’s surface = 2.67g/cc - The study of earthquakes led to the understanding of the layers of the earth - When rocks in the subsurface break up and slip along a fault, they generate shock waves that travel outward to form an earthquake Layers of Earth - Changes in depth o Pressure increases o Temperature increases
Image of page 8
o Geothermal gradient: The rate at which T changes with depth. Geothermal gradient DECREASES with depth. The crust - The earth’s crust floats on a denser mantle - Continental crust is thicker, less dense - Oceanic crust is thinner, more dense The mantle - Solid rock, 2885km thick, 82% of the Earth’s volume - Convecting - Moho: the line that splits the crust and the mantle The core - Iron rick sphere with radius of 3400 km - Seismic waves segregate two radically different parts - The outer core is liquid, inner core is solid (greater pressures keep the inner core solid) Lithosphere-Asthenosphere - Lithosphere: the outermost 100-150 km of Earth o Behaves rigidly, as a non-flowing material o Composed of crust and upper mantle o Material that makes up the tectonic plates - Asthenosphere: upper mantle that is below the lithosphere o Shallow under oceanic lithosphere, deeper under continental o Flows as a soft solid Two types of lithosphere - Continental: 150 km thick o Felsic to intermediate crustal rocks o Lighter, less dense o More buoyant – floats more - Oceanic: 100 km thick o Mafic crust: Basalt and gabbro o Heavier more dense o Less buoyant (sinks more) Lecture 4 – Layers of the Earth & Tectonic Plates - 0 on a topographical map is sea-level - The temperature of the earth increases with increasing depth - Atmosphere increases then decreases and then increases again
Image of page 9
- The velocity of a seismic wave changes at increasing depths, and at a certain depth the change is abrupt (moho) Plate tectonics - Earth’s lithosphere can be broken into 20 plates that interact (12 major plates, many microplates) - Each plate is a piece of the lithosphere and can have both continent and ocean environments. Oceanic and Continental Lithosphere Systems - Broken into many pieces or “plates” - Character is different in continental and oceanic environments - A plate can contain both environments Continental drift - Continental drift was the precursor to the theory of plate tectonics - Tectonics: the study of large scale movements and deformation of the Earth’s lithosphere. Evidence - Glacial evidence o Evidence of glaciers found on five separated continents 180 million years ago. - Paleoclimatic evidence o Placing Pangaea over the Late Paleozoic South pole o Wegener predicted rocks defining Pangaea climate belts Tropical coals Tropical reefs Subtropical deserts Subtropical evaporates - Fossil evidence o Fossils of identical species found on widely separated land (nonswimming mammals) - Matching mountain belts o Distinctive rock assemblages and mountain belts match across the Atlantic Lecture 5 – Continental Drift Criticisms of Wegener’s Ideas - Wegener had multiple lines of strong evidence - He couldn’t explained how or why the continents moved
Image of page 10
Image of page 11

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture