Ayats(Signs) in the Universe series, no. 3
The dynamic, roiling, rumbling surface of the earth:
Sura 27, Ayat 88: "Thou seest the mountains and thinkest them firmly fixed: but they shall pass away as the clouds pass away: (such is) the artistry of God, who disposes of all things in perfect order: for he is well acquainted with all that ye do."
Recently we have witnessed how Mount Merapi in Indonesia has been stirring to life, spewing volcanic ash and lava. We also saw, around the same time, an earthquake strike Java province not far to the west of the active volcano. We all also remember the devastating earthquake and tsunami off Sumatra province in 2004.
I bring this up because the sight of another mountain range as I was driving from Toronto to Washington DC over the Victoria Day long weekend jogged my memory of how the earth we live on is not static but very dynamic and that volcanoes, earthquakes and mountain ranges are connected in ways that were only fully discovered in the mid-1960s.
I was driving past the Appalachian mountain range in Pennsylvania and it occured to me that this range was once taller than the Himalayas are today. All this earthly dynamism is the result of a phenomenon called plate tectonics, which was one of the great scientific discoveries of the 20th century. The plate tectonics revolution resulted primarily from the merging of six seperate lines of observational evidence:
1) The similarly shaped coastlines of Africa and Europe compared to North and South America;
2) Major deposits of rocks, minerals and fossils seem to match up exactly accross the Atlantic ocean, like pieces of a jigsaw puzzle;
3)The non-uniform distribution of earthquakes and volcanoes, which tend to lie along narrow belts around the globe;
4)Ocean floor topography, including an astonishing chain of mountains called the Mid-Atlantic Ridge;
5)The ages of volcanic islands in the Atlantic ocean, and,
6)Sea-floor magnetic data.
The resulting theory of plate tectonics states that the Earth's surface is broken up into about a dozen tectonic plates, which are relatively thin, brittle slabs of rock no more than 100km thick, but up to thousands of km accross.. The energy to move all these plates comes from the hot, plasticised rocks undergoing convection movement in the earth's mantle.
The tectonic plates are seperated by three types of boundaries:
a)Divergent boundaries, where new crust forms: The mid-Atlantic mountain range is under the Atlantic ocean and is the longest mountain range on earth, which runs the full length of the North and South Atlantic oceans, almost exactly half way between the continents and roughly parallel to the curving coastlines. This mountain range is where new earth crust is formed on the surface of the ocean floor and spreads laterally outwards in both directions, a mechanism that could explain the opening of the Atlantic ocean; this boundary is now spreading outwards at about 2 to 4 cm per year. At this rate of spreading, the Atlantic began to open up 200 million years ago. Before this time there was no Atlantic ocean and all four continents were crunched up against each other, forcing the Appalachian mountain chain to go upwards and be even taller than the Himalayas are today. Another major divergent boundary in the South Pacific ocean is spreading as much as 17cm per year.
b) Convergent boundaries, where crust plunges back into the earth's mantle: This process occurs in those areas around the Pacific rim, where earthquakes and volcanoes occur in proximity. When one of the converging plates carries thin ocean crust as opposed to thicker continental crust(as in the Indonesian or Java plate boundary), the oceanic material plunges into the mantle in a process called subduction. Subduction zones are associated with numerous deep earthquakes, as well as intense volcanism, inland of the subduction zone by about 70 to 100km. Hence Mount Merapi is about 100km to the east of the recent earthquake fault line. I saw a news clip yesterday that said that, as a result of the recent earthquake, the volcano has become even more active, underlining the intimate connection between the volcano and the nearby tectonic plate boundary. Mount St. Helens, which had a blistering eruption in 1980, is also about 100km to the east of the North west pacific tectonic plate boundary. The Andes mountain range in South America frequently has volcanic eruptions and this range is, again, about 100km inland from its fault line. Mount Pinatubo in the Phillipines is about 100km to the west of the Pacific tectonic plate and is part of the circular 'Ring of Fire' that surrounds the Pacific ocean. The picture of the Alaskan volcano I posted before this post is also part of this ring of fire, ocupying the northern part of the 'Ring'.
c) Transform boundaries are faults where two plates slide laterally past each other not under or over each other. The San Andreas fault on the west coast of Canada and the U.S.A. is the longest highly active tranform boundary.
Not all volcanoes arise in intimate relation to a tectonic plate boundary. Some well-known volcanic areas, including Hawaii and Yellowstone National Park are in the middle of a tectonic plate and not near a boundary. They are above what are called 'hot spots' from deep within the earth's mantle about 3000km down. As the Pacific Plate moves over the fixed Hawaiian hot spot, new Hawaiian islands are formed.
We can see that the surface of the earth is a place of roiling activity that sees crust get sucked back into the mantle at some points on the earth and new crust ooze back out onto the surface from the mantle at other points on earth. The whole process is driven by the earth's own inner heat from the mantle. Volcanoes and earthquakes are a consequence of this roiling activity. This is how the earth renews itself over millions of years.
The following exerpt of a speech by Mowlana Hazar Imam captures the essence of the knowledge of the above-described object and event in nature: "Indeed, one strength of Islam has always lain in its belief that creation is not static but continuous, that through scientific and other endeavours, God has opened and continues to open new windows for us to see the marvels of His creation." [Speech 16 March 1983] -- Aga Khan IV.
easynash
Islam, eminently logical, placing the greatest emphasis on knowledge, purports to understand God's creation:Aga Khan 4.
The God of the Quran is the One whose Ayats(Signs) are the Universe in which we live, move and have our being:Aga Khan 3
