The evolution of land plants took place about 430 million years ago during the Silurian Period, when North America and Europe were conjoined in a landmass called Pangaea.
[...] "Plants caused fundamental changes to river systems, bringing about more meandering rivers and muddy floodplains, as well as thicker soils," says Dr Christopher Spencer, Assistant Professor at Queen's University in Kingston, Ontario, lead author of the study. "This shift was tied to the development of plant rooting systems that helped produce colossal amounts of mud (by breaking down rocks) and stabilised river channels, which locked up this mud for long periods."
The team recognised that Earth's surface and deep interior are linked by plate tectonics – rivers flush mud into the oceans, and this mud then gets dragged into the Earth's molten interior (or mantle) at subduction zones where it gets melted to form new rocks.
"When these rocks crystallise, they trap in vestiges of their past history," says Dr Tom Gernon, Associate Professor of Earth Science at the University of Southampton and co-author of the study. "So, we hypothesised that the evolution of plants should dramatically slow down the delivery of mud to the oceans, and that this feature should be preserved in the rock record – it's that simple."
[...] The team uncovered compelling evidence for a dramatic shift in the composition of rocks making up Earth's continents, which coincides almost precisely with the onset of land plants.
Notably, the scientists also found that the chemical characteristics of zircon crystals generated at this time indicate a significant slowing down of sediment transfer to the oceans, just as they had hypothesised.
[...] "It is amazing to think that the greening of the continents was felt in the deep Earth," concludes Dr Spencer.
Journal Reference:
Spencer, C.J., Davies, N.S., Gernon, T.M. et al. Composition of continental crust altered by the emergence of land plants. Nat. Geosci. (2022). 10.1038/s41561-022-00995-2
(Score: 3, Disagree) by bzipitidoo on Monday September 12 2022, @01:42AM (3 children)
I have this notion that life made and grew land masses thanks to all the erosion it slowed and prevented. And that this goes back before plants, to bacterial filaments, sheets, and stromatolites.
One thing about the summary: Pangaea didn't exist during the Silurian. It assembled later.
(Score: 2) by PiMuNu on Monday September 12 2022, @07:13AM
> I have this notion that life made and grew land masses
What is your evidence for this?
(Score: 2) by aafcac on Monday September 12 2022, @12:29PM
Probably not, the kind of plants that can handle being out of water aren't necessarily the same ones that can handle being completely submerged. I'm sure that plants did play a role in keeping the land somewhat protected on the edges, but if there weren't other significant factors at play, we'd probably have a fraction of the landmass that we've got. There's plenty of places where there's multiple feet of land being eroded every year and plants are going to have a tough time keeping up with that.
(Score: 2) by Immerman on Monday September 12 2022, @03:46PM
That's undermined by the fact that Earth had continents for several billions of years before plants colonized them in the last half-billion.