Featured Answers

0
Active contributors today

Answer:

Both of these mountain ranges were created (and are still growing) because of tectonic plates colliding. There is one significant difference between them though, as we shall see below.

Explanation:

One of the ways in which mountain ranges can be built is when tectonic plates collide.

The continent of India was on its own plate, and was joined to the supercontinent called Gondwana. When Gondwana broke up, India was carried northward by tectonic forces, and eventually 'crashed' into Asia. It is still moving north at the rate of about 5 cm per year. This has resulted in a (still growing) mountain range which is made of continental crust rising at the junction between these two plates.

Because it is made up of continental crust on both sides (Indian & Asian), it's lighter than oceanic crust. So, there is almost no subduction, and hence no volcanic activity in the zone (although there are earthquakes). These mountains are being 'bulldozed' up. In some places, the crust may be as thick as 70 odd km.

The Rocky Mountains (like the Andes), are the result of another type of plate collision. In this case, a continental plate meeting an oceanic one. In the case of the Rockies, this is because the N American plate is moving roughly west-southwest at about 2.3 cm per year.

This causes subduction because continental crust is lighter, and rides over oceanic crust, thus pushing the oceanic crust down into the mantle, where it melts, and eventually forces its way back up to the surface as lava.

If you're not sure what subduction is, this slide explains it:
image.slidesharecdn.com

It is from image.slidesharecdn.com.

Answer:

In several different ways and they combine in interesting ways. I've linked in a video that does a nice job of explaining the various orbital wobbles:

Explanation:

The Earth has a lot of wobbles and such in its orbit around the Sun. Three things that these wobbles affect are:

orbital eccentricity - or how close to a circle the Earth moves around the Sun

http://www.indiana.edu/~geol105/images/gaia_chapter_4/milankovitch.htm

axial obliquity - or how far the Earth tilts in its axis
http://www.indiana.edu/~geol105/images/gaia_chapter_4/milankovitch.htm
precession - which is the wobble that has the axis point in different directions

http://www.indiana.edu/~geol105/images/gaia_chapter_4/milankovitch.htm

This youtube video explains in detail how all this happens:

detailed video of Earth orbital wobbles

http://www.mnn.com/earth-matters/climate-weather/stories/everything-you-need-to-know-about-earths-orbit-and-climate-cha

You may want to read up on Milankovitch cycles.

Answer:

Much remains to be learned about lightning, but I try below to give the essentials...

Explanation:

Lightning starts with the accumulation of large amounts of charge in a thundercloud. This charge results from droplets of water being blown upwards through particles of ice in the higher layers of the cloud. The result is a buildup of positive charge high in the cloud, with negative charge in the lower portions.

Once the charge reaches a critical level (I'm not aware of whether this level has been reliably measured), electrons can cause ionization of molecules in the air, and a conducting path begins. The negative ions travel a short distance along this path, then stop and accumulate for a short while, before starting off again in a new direction. This process repeats over and over as the path of ionized air zig-zags its way toward the ground. This is not the lightning bolt at this stage, it is a leader that creates a path that the bolt will later follow.

Once the downward charge reaches a perhaps a hundred meters from the ground, the negative charge buildup begins to cause positive "streamers" to emerge from objects in the ground.

Check this video - shot in my hometown :)

It is the streamer that connects with the downward negative charge leader that "closes the switch" and completes an electric path that allows the charge to drain from the cloud above.

This image shows it well

http://www.ux1.eiu.edu/~cfjps/1400/shockinglecture.html

Here is a great explanation from the Discovery Channel

Answer:

When the location is angled towards the sun, it gets longer days and higher temperatures. When angled away, days are shorter and cooler.

Explanation:

The earth rotates on an axis but the North-South axis is not "vertical" but tilted slightly. As the earth orbits the sun, the axis doesn't change.

June-July
The Northern Hemisphere faces the sun while the Southern Hemisphere is facing away from the sun. Temperatures north of the equator will be higher and the days will be longer.

September-October
The Northern and Southern Hemispheres face the sun equally.

December-January
The Northern Hemisphere faces away from the sun while the Southern Hemisphere faces toward the sun. Temperatures north of the equator will be lower and days will be shorter.

March-April
The Northern and Southern Hemispheres face the sun equally.

nasa.gov

More info: NASA SpacePlace

Answer:

Generally when a mineral's surface reflects light we say that it has luster.

Explanation:

Before we look at specific minerals let’s explore what exactly we mean when we say something "has luster".

When it comes to minerals there are two major types of luster: metallic and nonmetallic.

--

First, we have metallic luster (we refer to these as the metallic minerals). The minerals that we say have metallic luster are opaque (you can't see through them) and shiny. A good example of a mineral that has metallic luster is gold.

enter image source here
Gold nugget.

Courtesy of: Chris Ralph; Obtained from: en.wikipedia.org Public Domain

The metallic minerals have one subcategory which we call submetallic minerals they exhibit submetallic luster. These minerals look like metals however due to weathering and corrosion they’ve become dull or less reflective, cinnabar is a good example of submetallic luster.

enter image source here
Cinnabar

Courtesy of: H. Zell (Wikipedia User); Obtained from: en.wikipedia.org Reused under: CC BY-SA 3.0

--

The second type of luster is nonmetallic luster (we call these minerals the nonmetallic minerals). Minerals that have nonmetallic luster, unlike their metallic counterparts, don't look like metals. Since nonmetallic minerals don't look like metals identifying them is a little less straightforward than identifying a metallic mineral. Lucky for us though scientists have divided the nonmetallic minerals into four subcategories. Without further ado, the three subcategories:

Adamantine (or Diamondlike) this first subcategory is probably the most well-known. We say that a mineral is adamantine when it has brilliance (the light it reflects appears really bright) and shine. They can be transparent or translucent (some light can pass through them but you can't see through them). Adamantine minerals are typically found at jewelry stores, a diamond is a good example.

enter image source here
Diamond

Courtesy of: Steve Jurvetson; Obtained from: en.wikipedia.org Reused under: CC BY 2.0

Minerals in the second subcategory, Dull (or Earthy) luster, can be tricky to identify. Minerals that we describe as having a dull luster reflect light poorly (you'll probably have pick up the mineral, put it under bright light, and take a close look to see that it does indeed reflect some light) and have a porous and coarse surface. A good example of a mineral with dull luster is a type of clay called kaolinite.

enter image source here
Kaolinite

Courtesy of: Rob Lavinsky; Obtained from: www.irocks.com Reused under: CC BY-SA 3.0

Vitreous luster, our third subcategory, is probably the most common type of luster. Vitreous means "glass-like", and like glass these minerals don't reflect vivid light like the minerals in the adamantine subcategory. Minerals that have vitreous luster can be transparent or translucent. Quartz is a great example of a mineral that has vitreous luster.

enter image source here
Quartz

Courtesy of: JJ Harrison; Obtained from: en.wikipedia.org Reused under: CC BY-SA 2.5

Our fourth and final subcategory of nonmetallic minerals displays what we call Greasy luster. Minerals that are categorized as greasy luster minerals look like they've been coated in grease or oil and can feel "greasy" (or really smooth, almost slippery) when touched. Opal is probably one of the more common examples of a mineral with greasy luster.

enter image source here
Opal

Courtesy of: Daniel Mekis; Obtained from: en.wikipedia.org Reused under: CC BY-SA 3.0

I hope this helped!

Answer:

A subduction zone is most likely to occur, resulting in mountain building, volcanos. and earthquakes.

Explanation:

A converging boundary is most likely a place where the heat of the convection currents in the mantle is moving downward. This downward movement of the heat also results in a downward movement of the crust.

As the oceanic crust is thinner and more dense than the continental crust it is the oceanic crust that is drawn ( pushed) down into the mantle and melted. This results in the destruction of the sedimentary layers and fossils of the oceanic crust.

As the oceanic crust is pushed down the continental crust overrides the oceanic crust and is pushed up. This result is mountain ranges being formed at the convergent boundary of an oceanic crust and a continental crust. Also the magma from the melted oceanic crust rises to the surface, resulting in volcano's along the edge of the convergent boundary.

The large movements of the tectonic plates result in earthquakes. By plotting the location and depth of the earthquakes the shape of the subduction zone can be seen. Near the boundary the earthquakes are near the surface. Further from the boundary the earthquakes are progressively deeper in the earth.

So at the converging boundary of an oceanic tectonic plate and a continental tectonic plate, the oceanic plate is subducted resulting in mountain building, volcanos and earthquakes. The sedimentary layers of the oceanic crust with its fossils are destroyed, melted and turned back into magma and the mantle.

View more
Questions
Ask a question Filters
Loading...
This filter has no results, see all questions.
×
Question type

Use these controls to find questions to answer

Unanswered
Need double-checking
Practice problems
Conceptual questions