This article is about the development of the continental drift hypothesis before 1958. For the contemporary theory, see plate tectonics. For the Russell Banks novel, see Continental Drift (novel). For the fourth film in the Ice Age franchise, see Ice Age: Continental Drift.

The continental drift of the last 150 million years

Antonio Snider-Pellegrini's Illustration of the closed and opened Atlantic Ocean (1858).[1]
Continental drift is the movement of the Earth's continents relative to each other, thus appearing to "drift" across the ocean bed.[2]The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed byAlfred Wegener in 1912, but his theory was rejected by some for lack of a mechanism (though this was supplied later by Arthur Holmes) and others because of prior theoretical commitments. The idea of continental drift has been subsumed by the theory of plate tectonics, which explains how the continents move.[3]
In 1858 Antonio Snider-Pellegrini created two maps demonstrating how the American and African continents might have once fit together.
Answer:
A categorical grant is used for a specific purpose, or category, for state or local spending. (Ex: natural disaster, airport building, crime fighting) that depends on state's population. Block Grants are given for general purposes that the states can use as they see fit (welfare, public health).
The reason why some igneous rocks are smooth and some are coarse is the manner in which they formed. We can simply divide the igneous rocks into intrusive and extrusive ones.
The intrusive igneous rocks are formed deep into the ground. The magma that has formed this rocks has been exposed to higher temperatures and pressures. That has led to a very slow cooling off of the magma. Because the magma has been cooling off slowly, the crystals had time and the right conditions to grow larger, thus making the intrusive igneous rocks coarse.
The extrusive igneous rocks are formed on the surface. They have been formed by the lava that once it come out on the surface has been exposed to much lower temperatures and pressures. That has led to very quick cooling off of the lava. Because the lava has cooled off quickly, the crystals didn't had time to grow in size, thus they have remained very small, almost unnoticeable, thus making the extrusive igneous rocks smoother.
Answer:
<u>June solstice 21 has day shortest of the year in the Southern Hemisphere.</u>
Explanation:
- Viewed from 24 hours format the south pole lies at 90 degrees from the equator and as a result, the rays of the sun fall at 23.5 angles. The day light at the south poles runs for about three months since the september equinox.
- Thus, Antarctic Circle is dark on the June Solstice. As the Antarctic circle is 66.5 degrees south hence the sun makes a brief appearance or the sun does not rise.
- Sun remains completely below the horizon this is thus known as the Midwinter’s Day. The phenomenon of Civil twilight, Nautical twilight and astronomical twilight is found here from 6 to 12 degrees of latitude.