This was split from the Anthropocene discussion, but I think it deserves some consideration, and its own thread. The issues here are pretty interesting, and warrant some seroius consideration.
As was said in the split posts, there isn't a consensus on this. However, as I have no respect for consensus science and have the relevant expertise, I simply don't care. :D So we can dismiss with that concept from the outset.
The first question we must ask is, what do stratigraphic names mean? Today they appear to be tied to absolute dates, meaning "251 to 65.4 million years ago) for the Mesozoic (ref). However, that's more or less a convenient coincidence, and in regards to the Cenozoic it's actually a hinderance to serious geological research. The reality is that the geologic time scale was established back when only relative dating was possible, and they were based on fauna. In essence, the geologic time scale is the practical application of the principle of Faunal Succession; the fact that we can tie numbers to it is convenient and useful, but not in any way necessary.
Unfortunately, when it started the time scale focused on EUROPEAN fauna. This became a serious problem when we started looking at fauna around the world. North American organisms are different from European ones, and different significant events occurred in North America than in Europe. This resulted in several geological time scales for the Cenozoic (prior to that, things were similar enough that the variation isn't TOO bad). Names like Blancian and Rancholabrean stand alongside Pliocene and Pleistocene. I'm not as familiar with the Asian Land Mammal Fauna Ages time scale; i've worked extensively with the North American one (NALMA).
Humans have a tremendous impact on the planet, and it's pretty clear when we enter into an area. This creates very useful marker beds--we know that the ecosystem shifted in certain ways at that point. And since that's all the previous ages are based on, I see no point in refusing to name a new one due to human activity. There are distinctive markers that indicate human presence (middens, anthroposols, etc), and since every other time period is defined by index fossils I see no reason to not use a prolific and very distinctive index fossil in this case.
The stability of the Holocene ecosystem is, in my opinion, a myth. There was a major die-off at the end of the Pleistocene; the Holocene is marked by a lack of mammalian megafauna in most places. This likely is due at least in large part to human activities. The fact that the Holocene isn't stable is evidenced by numerous lines of evidence; for example, we don't see the vegitation stabilizing in response to the loss of the megafauna (I have personal experience with that--yuccas HURT). In my opinion, the Holocene is a transitional period between the Pleistocene and the Anthropocene.
This isn't really that unusual in the rock record; major faunal turn-overs always take time. However, for most of the past that amount of time is a rounding error; it's simply not something we can detect. The more recent the rocks, the more fine detail we can ascertain. This means that we can sub-divide more recent rocks more finely. That IS a problem, because the very act of calling the Holocene an epoch implies that it is in some way equal to things like Miocene. The transitional period between two epochs simply isn't, however; there is a distinct difference between epochs and transitional periods. We can quibble over whether to call it Pleistocene or Anthropocene (good arguments can be made either way, and let's face it, placing hard lines in gradational data always leaves room for debate), but the Holocene isn't an epoch.
Finally (mostly because I don't want to get involved in climate debates, which these discussions always seem to focus on), stratigraphy isnt' consistent. We still use the terms Quaternary and Tertiary, particularly in vertebrate paleontology, despite the fact that that entire nomenclature has been abandoned. The simple fact is that "Quaternary" and "Tertiary" are useful terms, so they continue to be used. So even if we agree it's not valid, that doesn't necessarily mean that it shouldn't be used.
This isn't exactly arm-chair or ivory-tower theorizing, either. There are significant fiscal impacts stemming from this discussion. Paleontological resources monitoring is a field growing in importance, and the distinction between the Quaternary and the Anthropocene is one that can save or cost companies--particularly renewable energy companies--hundreds of thousands of dollars. This has implications for energy independence and reliance on fossil fuels (those generating plants are always much smaller than renewable energy plants, and therefore impact less sediment). I don't base my views on client needs; however, I do acknowledge that this apparently purely academic question has some pretty substantial real-world implications.
One really cool aspect of this question is that we get to study a transition more or less as it happens. And what we find is that the transition isn't simultanious around the globe. It happens in fits and starts, and in different areas at different times. There are parts of Africa where a good argument could be made never came out of the Pleistocene. In contrast, New York City is most definitely firmly in the Anthropocene, with the establishment of purely Anthropocene ecologies, drainages, etc. This has implications for understanding previous mass extinctions. We tend to think of them as happening all at once, but the reality is that they were geographic as well as temporal events. This is born out by European reefs across the K/Pg boundary, and studies of Antarctic fossils across that boundary (the one I'm most familiar with). Global events are mitigated or exacerbated by regional and local conditions; this results in the world moving into new geologic times at different times in different places. And that in turn has implications for recovery, particularly in terms of refugia. So even from a purely ivory-tower standpoint the term Anthropocene has some pretty important implications.
As was said in the split posts, there isn't a consensus on this. However, as I have no respect for consensus science and have the relevant expertise, I simply don't care. :D So we can dismiss with that concept from the outset.
The first question we must ask is, what do stratigraphic names mean? Today they appear to be tied to absolute dates, meaning "251 to 65.4 million years ago) for the Mesozoic (ref). However, that's more or less a convenient coincidence, and in regards to the Cenozoic it's actually a hinderance to serious geological research. The reality is that the geologic time scale was established back when only relative dating was possible, and they were based on fauna. In essence, the geologic time scale is the practical application of the principle of Faunal Succession; the fact that we can tie numbers to it is convenient and useful, but not in any way necessary.
Unfortunately, when it started the time scale focused on EUROPEAN fauna. This became a serious problem when we started looking at fauna around the world. North American organisms are different from European ones, and different significant events occurred in North America than in Europe. This resulted in several geological time scales for the Cenozoic (prior to that, things were similar enough that the variation isn't TOO bad). Names like Blancian and Rancholabrean stand alongside Pliocene and Pleistocene. I'm not as familiar with the Asian Land Mammal Fauna Ages time scale; i've worked extensively with the North American one (NALMA).
Humans have a tremendous impact on the planet, and it's pretty clear when we enter into an area. This creates very useful marker beds--we know that the ecosystem shifted in certain ways at that point. And since that's all the previous ages are based on, I see no point in refusing to name a new one due to human activity. There are distinctive markers that indicate human presence (middens, anthroposols, etc), and since every other time period is defined by index fossils I see no reason to not use a prolific and very distinctive index fossil in this case.
The stability of the Holocene ecosystem is, in my opinion, a myth. There was a major die-off at the end of the Pleistocene; the Holocene is marked by a lack of mammalian megafauna in most places. This likely is due at least in large part to human activities. The fact that the Holocene isn't stable is evidenced by numerous lines of evidence; for example, we don't see the vegitation stabilizing in response to the loss of the megafauna (I have personal experience with that--yuccas HURT). In my opinion, the Holocene is a transitional period between the Pleistocene and the Anthropocene.
This isn't really that unusual in the rock record; major faunal turn-overs always take time. However, for most of the past that amount of time is a rounding error; it's simply not something we can detect. The more recent the rocks, the more fine detail we can ascertain. This means that we can sub-divide more recent rocks more finely. That IS a problem, because the very act of calling the Holocene an epoch implies that it is in some way equal to things like Miocene. The transitional period between two epochs simply isn't, however; there is a distinct difference between epochs and transitional periods. We can quibble over whether to call it Pleistocene or Anthropocene (good arguments can be made either way, and let's face it, placing hard lines in gradational data always leaves room for debate), but the Holocene isn't an epoch.
Finally (mostly because I don't want to get involved in climate debates, which these discussions always seem to focus on), stratigraphy isnt' consistent. We still use the terms Quaternary and Tertiary, particularly in vertebrate paleontology, despite the fact that that entire nomenclature has been abandoned. The simple fact is that "Quaternary" and "Tertiary" are useful terms, so they continue to be used. So even if we agree it's not valid, that doesn't necessarily mean that it shouldn't be used.
This isn't exactly arm-chair or ivory-tower theorizing, either. There are significant fiscal impacts stemming from this discussion. Paleontological resources monitoring is a field growing in importance, and the distinction between the Quaternary and the Anthropocene is one that can save or cost companies--particularly renewable energy companies--hundreds of thousands of dollars. This has implications for energy independence and reliance on fossil fuels (those generating plants are always much smaller than renewable energy plants, and therefore impact less sediment). I don't base my views on client needs; however, I do acknowledge that this apparently purely academic question has some pretty substantial real-world implications.
One really cool aspect of this question is that we get to study a transition more or less as it happens. And what we find is that the transition isn't simultanious around the globe. It happens in fits and starts, and in different areas at different times. There are parts of Africa where a good argument could be made never came out of the Pleistocene. In contrast, New York City is most definitely firmly in the Anthropocene, with the establishment of purely Anthropocene ecologies, drainages, etc. This has implications for understanding previous mass extinctions. We tend to think of them as happening all at once, but the reality is that they were geographic as well as temporal events. This is born out by European reefs across the K/Pg boundary, and studies of Antarctic fossils across that boundary (the one I'm most familiar with). Global events are mitigated or exacerbated by regional and local conditions; this results in the world moving into new geologic times at different times in different places. And that in turn has implications for recovery, particularly in terms of refugia. So even from a purely ivory-tower standpoint the term Anthropocene has some pretty important implications.
via JREF Forum http://ift.tt/1euBxI0
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