Best Answer

it show 8km is oceanic crust and 40km is continental crust

User Avatar

Wiki User

11y ago
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: The earths crust varies from 8km to 40 km what does this show?
Write your answer...
Still have questions?
magnify glass
Continue Learning about Earth Science

How much of gold is in the earths crust?

we dnt no :) We can only estimate. There are two types of crust: continental and oceanic. By volume the continental makes up about 70% and the oceanic makes up about 30%. Continental crust varies from 30 to 70km thick (with an avearge of 40km or so) and has an average density of 2.7 g/cm^3. Oceanic crust varies from 5 to 10km thick (with an average of 8km or so) and a density of about 3.3 g/cm^3. We can calculate the weighted average for the thickness of the total crust and get an estimate of about 30.4 km: 70% * 40 km + 30% * 8 km = 30.4km Calculate the volume of the total crust as the difference between the total volume of the Earth and the volume less the crust. Using an average radius on Earth of 6371km: 4/3 * pi * (6371 km^3 - 6340.6 km^3) = 1.54321 *10^10 km^3 = 1.54321 *10^19m^3 Remember that by volume this is 70% continental and 30% oceanic. Using this and the densities given above we can calculate the masses of each part of the crust: Continental: 1.54321 *10^19 m^3 * 70% * 2700 kg/m^3 = 2.92 * 10^22 kg Oceanic: 1.54321 *10^19 m^3 * 30% * 3300 kg/m^3 = 1.53 * 10^22 kg This gives a total bulk mass of the crust of around 4.45 * 10^22 kg. A quick search on the internet tells me that the average gold grade in the bulk crust is 0.0011 ppm gold. This equates to 0.0011 grams of gold per tonne of crust. So: 4.45 * 10^22 kg = 4.45 *10^19 tonnes 4.45 * 10^19 tonnes * 0.0011 g/tonne = 4.90 * 10^16 g of gold This works out to approximately 50 billion tonnes of gold, or at current gold prices (~$1200/ounce) approximately $2,000,000,000,000,000,000! (of course with that much gold available, I doubt gold prices would stay at $1200 an ounce). Of course the are all estimates, but the moral of the story is that if you could find a way to economically extract this gold, you would be a very rich person.

What is the Moho or Mohorovicic Discontinuity?

The Mohorovicic discontinuity, usually referred to as the Moho, is the boundary between the Earth's crust and the mantle. The Moho serves to separate both oceanic crust and continental crust from underlying mantle. The Moho mostly lies entirely within the lithosphere; only beneath mid-ocean ridges does the Moho also define the lithosphere-asthenosphere boundary. The Mohorovicic discontinuity was first identified in 1909 by Andrija Mohorovicic, a Croatian seismologist, when he observed the abrupt increase in the velocity of earthquake waves (specifically P-waves) at this point.The Mohorovicic discontinuity is about 5 km below the ocean floor and 30 to 50 km beneath typical continents. The Moho is deepest beneath the Tibetan Plateau, where it is approximately 75 km below the surface.[

What is the atmospheric pressure in the troposphere?

The troposphere is the lowest layer of the earth's atmosphere and is the one that contains weather and which can support life. Its upper limit is the highest point that the suns heat can cause warm and moist air to reach. This means that the troposphere extends to a much higher altitude in the tropics than near the cooler poles - between 15km (9 miles) to 8km (5 miles). Atmospheric pressure varies from around 1000 kpa (14 pounds per square inch, PSI) at sea level down to about 200 kpa (3psi) at about 10km.

What are two facts about the troposphere?

- The troposphere is the lowest part of Earth's atmosphere. - It contains about 75% of the atmosphere's mass. - It also contains about 99% of the atmosphere's water vapour and aerosols. - Most weather phenomena occur in the troposphere. - It ranges in thickness from 8km at the poles to 16km over the equator.

Where is the biggest rock in the world?

The largest rock in the world is Mt Augustus (Burringurrah, as it is known by Wajarri Yamatji traditional owners), in Western Australia, located inland, east of Carnarvon, and about 850km north of Perth. It is more than twice the size of Ayers Rock (Uluru). It rises 717 metres above the stony desert, and extends for a length of 8km - almost the entire circumference of Uluru. (Some sources say Mt Augustus is 858m in height, but Western Australia's Department of Conservation and Land Management states 717m.) It does not attract the same tourist numbers because it contrasts less dramatically with its surroundings, and does not have the colour changes that Ayers Rock displays during the days and seasons.