That didn't bother me nearly as much as how they know other planets don't have plate tectonics.
This isn't entirely true, the geomorphology of several planets and celestial bodies (portions of Mars and some of the moons of Jupiter and Saturn) show evidence of tectonic activity. It is believed that tectonics halted on Mars with the loss of her atmosphere thus the loss of liquid water.
Also, how do they know the percentages of identified/unidentified species????
This is a ballpark assumption and probably the most inaccurate stat on the infographic. Probably derived from biomass calculations or some obscure other calculation with several variables.
Also, how do they know to the exact point how long the earth has had oxygen.
This is very easy: Banded Iron Formations (BIFs). Oxygen had to be at certain concentrations to precipitate out the iron necessary in these formations. There would be periods of rapid precipitation resulting in a large drop in the concentration of oxygen. This would produce the more "cherty" layer. Repeat and rinse several times as the concentration slowly builds up and most iron in the oceans is depleted. WikiLink BIFs
Also, how do they know the continents move 2cm a year?
Very easy as well. This is the rate of the spread at the Mid-Atlantic Ridge (MAR). This was initially calculated by the dating of the paleomagnetic striping of the ocean floor (evidence of the Earth's magnetic poles swapping polarities throughout history) and simply calculating spreading rates. Now it is done with high precision GPS receivers on several points through continents. I worked with a project called EarthScope
one summer installing these receivers at various points in the US to calculate interplate movement within the western continental margin.
The East Pacific Rise, off the western coast of South America, is actually the fastest spreading center on Earth with spreading rates between 5-6 cms a year.
The more you know
This post was edited on 6/30 at 8:29 am