New answers tagged geochemistry
0
If you enlarge the picture and follow a line at 1 o'clock from the weirdly shaped piece in question, a few feet away from it at the back of an imaginary 'man's head' rock, you will see a similar convoluted piece. Now follow a line at 10 o'clock from our original specimen, and also a few feet away is a longer,straighter piece in the process of eroding from ...
1
What you can see in the bottom picture is sandstone/mudstone/claystone.
If you look at the bottom picture top right you can see a thin rock that has split off, this is how a rock splits after it has been heated and then suddenly gets cooled down as it does on Mars when the Sun goes down.
On Earth the change in temperature is too slow for this to happen in ...
2
My speculation is that if you try to use ma% or mas%, you will be asked to change it to wt%, because what you are proposing is not yet standard usage.
If I came across ma%, my initial though would be "what does that mean". My second thought would be, "does it mean milli annums percent?", (thousandsths of a year percent) - which would be meaningless to me.
...
0
The Role of Plate Tectonic-Climate Coupling and Exposed Land Area in the
Development of Habitable Climates on Rocky Planets cites a few references for the global carbon cycle model.
The diagram on page 8 seems to imply that subduction is the only sink.
0
There aere too many unknowns to give reliable figures for the varying levels of oxygen in the atmosphere in Precambrian times. What can be said with a fair degree of certainty is that photosynthetic cyanobacteria evolved about 3.5 billion years ago. At first the oxygen they produced was absorbed by the ocean, but by about 3 billion years ago it began to ...
Top 50 recent answers are included
