Idea from a science TV show tonight. Looks dubious to me.

Lichen is mostly responsible for the Earth’s land, without lichen there would be much less land above the sea surface.

The timing is uncertain, they could mean now, or they could mean 500 million or a billion years ago.

The reasoning goes as follows.

• Lichen is excellent at breaking raw volcanic rock down into clay.
• The clay is washed down into the ocean.
• The clay is excellent at holding water.
• The clay holding water is dragged down by plate tectonic subduction.
• The subducted water aids the fluidity of the magma
• Which spews more lava creating mountain ranges.

mollwollfumble said:

Idea from a science TV show tonight. Looks dubious to me.

Lichen is mostly responsible for the Earth’s land, without lichen there would be much less land above the sea surface.

The timing is uncertain, they could mean now, or they could mean 500 million or a billion years ago.

The reasoning goes as follows.

• Lichen is excellent at breaking raw volcanic rock down into clay.
• The clay is washed down into the ocean.
• The clay is excellent at holding water.
• The clay holding water is dragged down by plate tectonic subduction.
• The subducted water aids the fluidity of the magma
• Which spews more lava creating mountain ranges.
  

I’d like to see their numeric estimates. Volcanic rock is broken down by any number of processes. And shit, if it didn’t break down in the first place it would already be above water.

dv said:

mollwollfumble said:

Idea from a science TV show tonight. Looks dubious to me.

Lichen is mostly responsible for the Earth’s land, without lichen there would be much less land above the sea surface.

The timing is uncertain, they could mean now, or they could mean 500 million or a billion years ago.

The reasoning goes as follows.

• Lichen is excellent at breaking raw volcanic rock down into clay.
• The clay is washed down into the ocean.
• The clay is excellent at holding water.
• The clay holding water is dragged down by plate tectonic subduction.
• The subducted water aids the fluidity of the magma
• Which spews more lava creating mountain ranges.
  

I’d like to see their numeric estimates. Volcanic rock is broken down by any number of processes. And shit, if it didn’t break down in the first place it would already be above water.

I’d like to see their numeric estimates, too. In a nutshell it boils down to what fraction of clays from igneous rocks are generated by biological processes as opposed to what fraction form chemical processes – a negligible fraction comes from physical processes.

Further down the sequence, there’s also the question of what fraction of water subduction comes from clays and what fraction from “ooze”. Calcarious ooze covers 48% of the world ocean’s floor, clay covers 38% of the ocean floor, and siliceous ooze covers the remaining 15%. But, however you slice it, living organisms are responsible for by far the majority of the water subducted by plate tectonics.

“Water at subduction zones is carried to mantle depths by the subducting oceanic plate and then released by dehydration. It then migrates upwards and contributes to melting of the mantle wedge to form primary arc magma. The magma thus captures and transfers water to the crust, or outgasses water to the atmosphere. Water, either in fluids or melts in both the slab and the mantle, promotes the dissolution and mobilization of elements and affects the physical properties of the sub-arc slab, mantle, and seismicity.” from https://www.sciencedirect.com/science/article/abs/pii/S0016703714002610

Heck, it almost looks as though there wouldn’t be much in the way of plate tectonics without living organisms of one type or another. Lichens or (or foraminifera, coccolithophores, pteropods, diatoms or radiolaria) help enormously with water subduction and the lubrication of plate tectonics.

“Lichen is mostly responsible for the Earth’s land, without lichen there would be much less land above the sea surface.”

digressing..

As I understood… lichen precedes soil which helps to collect grains of dust and dirt and particles from areas surrounding bare rock , which then in turn aids the collection of soils and increased moisture levels , which provides the growing conditions for the the development off moss. This then allows for plant species to take root and so on after that.

If the climate changed tomorrow and inhibited or the forced extinction of lichen and moss then the cycle of dead volcanoes , rock platforms/ rock eruptions , water /wind erosion , lichen , moss and forestation , would be broken as I understand things.

That’s the trouble with lichen…

I mean lichen have been around maybe 400 million years. There was plenty of land before that. (Shrugs)

dv said:

I mean lichen have been around maybe 400 million years. There was plenty of land before that. (Shrugs)

Another belief was the fluttering of a butterfly in a rain forest, could create terrible storms on the other side of the world. There will always be gullible people.

PermeateFree said:

dv said:

I mean lichen have been around maybe 400 million years. There was plenty of land before that. (Shrugs)

Another belief was the fluttering of a butterfly in a rain forest, could create terrible storms on the other side of the world. There will always be gullible people.

I know chaos theory. “Could” is correct, for exponentially small values of “could”. Like a probability in order of 2^250 : 1 against.

> There was plenty of land before that.

OK. To go back to the TV program. The statement was that the land before living things (not specifically lichen) was just a single large island, with most of the Earth’s surface below sea level.

Continental drift evidence gives us:
“Pangaea came together about 300 million years ago. If you go back before Pangaea there were earlier supercontinents, such as Rodinia, which existed 750 million to 1.1 billion years ago, and Columbia, at 1.5 to 1.8 billion years ago.”

A test for the hypothesis would be the ratio of volcanic to plutonic rocks in Rodinia and Columbia, is it less than today? Or alternatively a measure of what proportion of Rodinia and Columbia were below sea level, more than today?

mollwollfumble said:

PermeateFree said:

dv said:

I mean lichen have been around maybe 400 million years. There was plenty of land before that. (Shrugs)

Another belief was the fluttering of a butterfly in a rain forest, could create terrible storms on the other side of the world. There will always be gullible people.

I know chaos theory. “Could” is correct, for exponentially small values of “could”. Like a probability in order of 2^250 : 1 against.

> There was plenty of land before that.

OK. To go back to the TV program. The statement was that the land before living things (not specifically lichen) was just a single large island, with most of the Earth’s surface below sea level.

Continental drift evidence gives us:
“Pangaea came together about 300 million years ago. If you go back before Pangaea there were earlier supercontinents, such as Rodinia, which existed 750 million to 1.1 billion years ago, and Columbia, at 1.5 to 1.8 billion years ago.”

A test for the hypothesis would be the ratio of volcanic to plutonic rocks in Rodinia and Columbia, is it less than today? Or alternatively a measure of what proportion of Rodinia and Columbia were below sea level, more than today?

> That’s the trouble with lichen…

LOL. John Wyndham

monkey skipper said:

“Lichen is mostly responsible for the Earth’s land, without lichen there would be much less land above the sea surface.”

digressing..

As I understood… lichen precedes soil which helps to collect grains of dust and dirt and particles from areas surrounding bare rock , which then in turn aids the collection of soils and increased moisture levels , which provides the growing conditions for the the development of moss. This then allows for plant species to take root and so on after that.

If the climate changed tomorrow and inhibited or the forced extinction of lichen and moss then the cycle of dead volcanoes , rock platforms/ rock eruptions , water /wind erosion , lichen , moss and forestation , would be broken as I understand things.

That’s a good point. Let me digress slightly to Surtsey.

“In the spring of 1965, the first vascular plant was found growing on the northern shore of Surtsey, mosses became visible in 1967, and lichens were first found on the Surtsey lava in 1970. Plant colonisation on Surtsey has been closely studied, the vascular plants in particular as they have been of far greater significance than mosses, lichens and fungi in the development of vegetation. Mosses and lichens now cover much of the island.”

“Insects arrived on Surtsey soon after its formation, and were first detected in 1964, When a large, grass-covered tussock was washed ashore in 1974, scientists took half of it for analysis and discovered 663 land invertebrates, mostly mites and springtails, the great majority of which had survived the crossing.”

“Birds first began nesting on Surtsey three years after the eruptions ended”, (in 1970?)

I’m lichen those odds

dv said:

I’m lichen those odds

It just keeps groan.

The Rev Dodgson said:

dv said:

I’m lichen those odds

It just keeps groan.

and groan.

PermeateFree said:

dv said:

I mean lichen have been around maybe 400 million years. There was plenty of land before that. (Shrugs)

Another belief was the fluttering of a butterfly in a rain forest, could create terrible storms on the other side of the world. There will always be gullible people.

Who knows what size butterflies lurk over the edge of the earth. ;)

roughbarked said:

PermeateFree said:

dv said:

I mean lichen have been around maybe 400 million years. There was plenty of land before that. (Shrugs)

Another belief was the fluttering of a butterfly in a rain forest, could create terrible storms on the other side of the world. There will always be gullible people.

Who knows what size butterflies lurk over the edge of the earth. ;)

I do.