All the layers are there. It is just that, for the layers of that time period, they were rotated / tilted so they are not horizontal, then they were ground off from above and below. So a huge amount is missing, but all layers are represented. I mention it in more detail in a comment further down. This diagram shows the area in question. It's layer B. https://play.google.com/books/... [google.com]
Its incorrect to say there are no rocks from that period. But they are rarer, and the unconformity is widespread. There are still pockets here and there of rocks from the period for whatever reason escaped whatever it was, probably glaciers . Some of them
To elaborate further some of the surviving rock from the period may have been offshore where the ice wouldn't have made contact with the rock, or they could have been in deep basins such as rift valleys , or rocks caught in subduction zones, or caught within thrust faults, where some rock had been pushed deeper into the crust in the subduction zone. I know some of the rocks from the period are in the UK and Nova Scotia which were coastal areas at the time like today, but were positioned of the coast of Africa.
by Anonymous Coward writes:
on Sunday September 05, 2021 @11:04AM (#61765653)
On one hand the article says there are no rocks from a billion years.
Poorly written.
There are rocks from that period, including with fossils. Some event certainly did happen and resulted in a really bizarre state of those rocks in the geological layer, so the article isn't completely talking out of its ass. Yet this particular statement about "no rocks" is incorrect.
If you look at their "Figure 1" image, layer 2 at the bottom is the one in question. It's turned partially sideways, for reasons unknown.
Normally we can infer fossils above other ones are more recent, and the fossils below are older. With this strange angle this doesn't always work all that well since fossils that used to be deeper can actually be closer to the surface in some places on earth, and much much deeper in other places on earth.
However there are fossils present, and they are at a frequency similar to below, which is far less frequent than the layers above. That's how we know there was life during that time, and we know from the many more fossils above that there was a few orders of magnitude more life after this period than the one before it. It's just very difficult to pinpoint exactly when within this angled layer the explosion of life happened.
Rock vs fossils (Score:5, Insightful)
On one hand the article says there are no rocks from a billion years.
On the other hand, it says that we know about animals back then.
But if there are no rocks, then what are those fossils from which we know about the animals?
Re:Rock vs fossils (Score:5, Informative)
All the layers are there. It is just that, for the layers of that time period, they were rotated / tilted so they are not horizontal, then they were ground off from above and below. So a huge amount is missing, but all layers are represented. I mention it in more detail in a comment further down. This diagram shows the area in question. It's layer B.
https://play.google.com/books/... [google.com]
Re:Rock vs fossils (Score:4, Informative)
Its incorrect to say there are no rocks from that period. But they are rarer, and the unconformity is widespread. There are still pockets here and there of rocks from the period for whatever reason escaped whatever it was, probably glaciers . Some of them
Re:Rock vs fossils (Score:4, Informative)
To elaborate further some of the surviving rock from the period may have been offshore where the ice wouldn't have made contact with the rock, or they could have been in deep basins such as rift valleys , or rocks caught in subduction zones, or caught within thrust faults, where some rock had been pushed deeper into the crust in the subduction zone. I know some of the rocks from the period are in the UK and Nova Scotia which were coastal areas at the time like today, but were positioned of the coast of Africa.
Re:Rock vs fossils (Score:5, Informative)
On one hand the article says there are no rocks from a billion years.
Poorly written.
There are rocks from that period, including with fossils.
Some event certainly did happen and resulted in a really bizarre state of those rocks in the geological layer, so the article isn't completely talking out of its ass. Yet this particular statement about "no rocks" is incorrect.
https://en.wikipedia.org/wiki/... [wikipedia.org]
If you look at their "Figure 1" image, layer 2 at the bottom is the one in question.
It's turned partially sideways, for reasons unknown.
Normally we can infer fossils above other ones are more recent, and the fossils below are older.
With this strange angle this doesn't always work all that well since fossils that used to be deeper can actually be closer to the surface in some places on earth, and much much deeper in other places on earth.
However there are fossils present, and they are at a frequency similar to below, which is far less frequent than the layers above.
That's how we know there was life during that time, and we know from the many more fossils above that there was a few orders of magnitude more life after this period than the one before it.
It's just very difficult to pinpoint exactly when within this angled layer the explosion of life happened.
Re: (Score:2)