Evaluating the Evidence for Continental Drift
There are several pieces of evidence certifying the existence of
continental drift. They include mid oceanic ridges, fitting of
continents, similarities of fossils on different continents and rock
matches.
The mid-oceanic ridges rise 3000 meters from the ocean floor and are
more than 2000 kilometres wide surpassing the Himalayas in size. The
mapping of the seafloor also revealed that these huge underwater
mountain ranges have a deep trench, which bisects the length of the
ridges, and in places is more than 2000 meters deep. Research into the
heat flow from the ocean floor during the early 1960s revealed that
the greatest heat flow was centred at the crests of these mid-oceanic
ridges. Seismic studies show that the mid-oceanic ridges experience an
elevated number of earthquakes. All these observations indicate
intense geological activity at the mid-oceanic ridges.
Periodically, the Earth's magnetic field reverses. New rock formed
from magma records the orientation of Earth's magnetic field at the
time the magma cools. Study of the sea floor with magnetometers
revealed "stripes" of alternating magnetisation parallel to the
mid-oceanic ridges.
This is evidence for continuous formation of new rock at the ridges.
As more rock forms, older rock is pushed farther away from the ridge,
producing symmetrical stripes to either side of the ridge. In the
diagram to the right, the dark stripes represent ocean floor generated
during "reversed" polar orientation and the lighter stripes represent
the polar orientation we have today. Notice that the patterns on
either side of the line representing the mid-oceanic ridge are mirror
images of one another. The shaded stripes also represent older and
older rock as they move away from the mid-oceanic ridge. Geologists
have determined that rocks found in different parts of the planet with
similar ages have the same magnetic characteristics.
The deepest waters are found in oceanic trenches, which plunge as deep
as 35,000 feet below the ocean surface. These trenches are usually
long and narrow, and run parallel to and near the oceans margins.
Method(data collection) ----------------------- If Long Shore Drift were taking place, I would expect to find: * Deposition of pebbles on one side of any obstruction. This obstruction could be a headland or an artificial barrier such as a groyne.
15. The pictures above show how the continents on Earth’s surface have changed position over a very long period of time. What explains this change? (S6E5e, f)
Yes this feature is the result of erosion and depositional processes however, it is not associated with the current water course. This feature may be the result of a Gilbert type delta that once occupied this area. Gilbert type deltas have three main components; topsets, foresets and bottomsets. Topsets are fluvial sediments (primarily sandur deposits) that were deposited on the subaerial delta surface. Erosive events occurring on the upper forslope can result in downslope channels and chutes. These features are then eroded by either strong currents or by debris flow resulting in these channels and chutes to become filled. Foresets are a combination of sand and gravel facies. The are deposited by gravitational processes on the delta foreslope and the grains tend to become finer and more angular downslope. Bottomsets consist of fine grained silts and clay and are deposited at the foot of the delta front.
Earthquakes are a natural part of the Earth’s evolution. Scientific evidence leads many geologists to believe that all of the land on Earth was at one point in time connected. Because of plate tectonic movements or earthquakes, continental drift occurred separating the one massive piece of land in to the seven major continents today. Further evidence supports this theory, starting with the Mid-Atlantic ridge, a large mass of plate tectonics, which are increasing the size of the Atlantic Ocean while shrinking the Pacific. Some scientists believe that the major plate moveme...
The coastal belt of the Franciscan Complex is composed of the youngest and least deformed units and makes up the western quarter of all Franciscan rocks. The rocks of the coastal belt are composed of arkosic sandstones, andesitic graywackes, and quartzofeldspathic graywackes interbedded with radiolarian chert (turbidite deposits) (Blake and Jones, 1981). These sedimentary rocks suggest a depositional environment of deep-sea fan systems with both oceanic and continental provenance. Parts of the belt show evidence of later metamorphism, principally due to subduction. Low-grade blueschist mineral facies are indicated by the presence of minerals such as laumonite and prehnite-pumpellyite (Blake and Jones, 1981). All rock units show evidence of thrust (imbricate) faulting due to the compressional forces of subduction. Ages of the coastal belt run from as little as 40 Ma (Eocene) to as old as 100 Ma (middle Cretaceous).
...ified rocks are usually inclined due to the structure folding and faulting because of the Paleozoic rock. (Adams, Butts, 23). Charles Butts states, “In its general relations the Paleozoic area of Alabama falls into the large geographic division of the eastern United States known as the Appalachian Highlands which extends from the Coastal Plain on the east to the Interior Lowlands of the Mississippi Valley region on the west.” (Adams, Butts, 43)
About 20 million years ago the last part of the Farallon sea floor plate subducted under the North American plate. This put the North American plate and the Pacific plate into contact, but unlike the Farallon sea floor plate, the Pacific plate sheared against the side of the North American plate. Because there was no plate subducting, the North American plate was in direct contact with the mantle (Tierney, 29). Heat from the mantle made the continental crust more ductile, which allowed the crust to extend and thin.
Primary coasts are divided into two categories: submergent and emergent coasts. Submergent coastlines result from a general sea-level rise and crustal subsidence. Most of the eastern United States has submergent coastlines. One example is the Chesapeake Bay. Emergent coastlines result from the land being lifted, either by tectonic activity or rebound from the weight of heavy glaciers, which exposes the former sea bottom bit by bit forming continuously new shoreline.
First you might need to know definition of tectonics. It is a theory in geology. The lithosphere of the Earth is divided into a small number of plates which float on and travel independently over the mantle and much of the Earth’s seismic activity occurs at the boundaries of these plates. That is the official definition of Plate tectonics. secondly, this plate covers many parts of continents. plate boundaries don’t go according to Continents boundaries, they make their own boundaries. The North American plat...
During the time of life and evolution, the land we walk on today has changed and developed into its current position. In 1912, Alfred Wegener, a German polar researcher, geophysicist and meteorologist, presented the idea of the world once being a supercontinent called Pangaea. Thenceforward, the landforms have split and drifted apart, known as continental drift. The philosophy that continents might have 'drifted' was first heard from by Abraham Ortelius in 1596. Through the change of physical geography, the land has affected societies, culture, and human beings. Because the land has moved and changed, people have had to adapt to their new style of living in order to survive.
Magnetic Field: The Earth has a superior magnetic field due to a core consisting of iron and nickel. Currently the rotation of the Earth and its Coriolis effect help to create this pull of the tides from the oceans. The northern lights or lurora Borealis can be seen at various times in a mystifying view of beauty.
...compasses to go haywire. Even less logical explanations such as alien attacks or particles from the city of atlantis affecting the magnetic field, exist, and are believed by some people. Other theories such as pirates, time vortexes, and methane hydrates are also thought to be a cause(http://adventure.howstuffworks.com/bermuda-triangle8.htm).
Plate tectonics is the theory that landmasses on tectonic plates are in slow constant movement due to convection currents in the mantle. Plate tectonics, or the movements of plates above the lithosphere (the most upper layer of earth's crust) can cause divergent, convergent,and transform boundaries.A boundary the way two tectonic plates collide. is Continental plates are plates that the continents are formed on. Oceanic plates are plates that the ocean covers, and the oceans form on top of these plates. Convergent boundaries and divergent boundaries are ways that these oceanic and continental plates interact with each other. Landforms are formed at boundaries. The landforms formed at boundaries depends on the type of plates that collide, and
inferred for the reservoir (4). The magma ascent to the surface occurred through a conduit of possibly 70 to 100 m in diameter (5). A thermal model predicts that such a reservoir should contain a core of partially molten magma (6) that can be detected by high-resolution seismic tomography.
Paleomagnetism is defined as the study of the record of the Earth’s ancient magnetic field using igneous and sedimentary rocks. It has been instrumental for our understanding of how planet Earth operates and is one of the cornerstones of plate tectonic theory. When rocks form, they record the direction, polarity, and absolute or relative intensity of the Earth’s magnetic field, which can be extracted with paleomagnetic methods. Paleomagnetism has several applications, most importantly it is used to reconstruct plate movements and plate tectonic configurations, and in magnetostratigraphy as a dating tool for sedimentary rocks. It can also provide information on the past behavior of Earth's magnetic field in absolute and relative paleointensity studies.