Thread: How much bigger is earth now compaired to 1 million yrs ago?

I was just want to see if anyone had an idea about how big earth is now compaired to like a million years ago. If one tiny seed can produce a forrest and that forrest is now dirt then it goes to say earth should be alot bigger.

The trees grow from the material around them (plus sunlight) and then release that back when they die. There is no net gain of mass.

The Earth does have several tons of dust fall onto it every day from space. Tons, you say? That sounds like a lot. Except the Earth is big. I did work it out once and, over the entire lifetime of the Earth, it came to something a couple of centimetres (if spread evenly over the surface).

Over 1 million years? A tiny fraction of a millimetre.

And then some of that gain in mass is offset by losses - mainly gas escaping the atmosphere.

BBC News - Who, What, Why: Is the Earth getting lighter?

Originally Posted by nathan adams

I was just want to see if anyone had an idea about how big earth is now compaired to like a million years ago. If one tiny seed can produce a forrest and that forrest is now dirt then it goes to say earth should be alot bigger.

The earth's mass grows by a very small amount each year due to space dust, and debris, but it hasn't changed much compared to the total mass of the earth.

All the mass of a tree is sourced from elements that are on the earth already and dead plant matter gets reused all the time in other forms of life. It doesn't add mass to the earth.

Edit: Damnit, Strange outdid me both in time and quality.

I thought Strange's estimate of size gain was out by a couple of orders of magnitude, but a quick calculation suggests that since about 3.5 billion years ago we should have acquired an average thickness of only about 11 cms.

If we go back earlier than that we are into the Late Heavy Bombardment phase when the planet was experiencing many large impacts over many millions of years that would have been been substantial in total.

Originally Posted by John Galt

I thought Strange's estimate of size gain was out by a couple of orders of magnitude ...

Maybe I was assuming the Earth was only 6,000 years old.

hmm... i don't think any truly new material is ever made. so all the mass existing now is ultimately derived from the Earth's formation.

so ALL water is recycled in some way, not just water somebody pisses in, and goes for treatment at the sewer plant..

Thank you all. That helps answer my question. I guess I was just wondering because there is layers of rock/soil and why is it that oil is so far under ground. and what about valcanos? when they erupt they create mountains that were not there before.

what about valcanos? when they erupt they create mountains that were not there before.

There were no mountains, or perhaps islands, on the surface but the materials that set in the cold air and water of the surface were already inside the magma beneath the surface. It's merely a relocation of materials and a transformation back from molten to solid. (Remember the stuff that's molten was once solid rock before it was melted.)