What a great way to prove to OP that the question wasn't stupid at all!

There's no evidence of this, but it's not just H. erectus that follows this pattern. There's a very clear transition of fauna between SE Asia and Australia that occurs in this region. The most famous division here is the Wallace line, which divides areas that were connected to the Asian mainland during the ice age from islands that remained separate, but early hominids actually dispersed a bit further, about to the Weber line. This is similar to elephants and some other large mammals, and implies they managed to cross short stretches of open water to reach these islands. But they apparently couldn't cross the larger gap between Timor and Australia.

It's worth noting that this dispersal happened during glacial periods when sea levels were lower and the geography of the area was quite different. You could walk all the way out to around Bali because sea levels were lower. And H. erectus and kin were all over south Asia and had been for more than a million years.

Really, it's not unusual to see that sort of spread. There's a fair amount of overlap between South Asian and African large mammals. When the Sahara is a grassland/savanna (which happens sometimes), large mammals with adaptable habits can disperse pretty easily between Africa and Asia, which is what you are seeing with hominins. But crossing the open ocean is much more difficult, and it seems that only modern humans managed it.

Here's a paper about hominins in SE Asia, which also has a map of sea levels and one of known hominin fossil sites

https://clas.uiowa.edu/sites/default/files/news-events/Larick-Ciochon-2015-Hominin%20Biogeography-ISEA-Evolutionary-Anthropology.pdf

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In my experience, 10% of geologists are very weird, 80% are slightly odd, and 10% are some of coolest people you will ever meet. I feel like u/CrustalTrudger might be in that last 10%. Great answer.

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Excellent answer and well put. What I love about science and things like this in general is there’s almost never a hard and fast answer. Not unlike this one, it’s usually a “eh, maybe?”.

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One could come up with a lot of issues, but I'll focus on three:

1. If we take an extremely simplistic view, faults are large but extremely narrow, i.e., effectively single fracture planes extending tens of kilometers into the crust. As such, the logistics of somehow injecting material to depths along these planes (which typically don't have an aperture in a normal sense) significantly below the deepest we've ever drilled are challenging (to put it mildly).

2. Faults represent locations where sufficient stress existed to break rocks and then to cause slip along the fracture plane (i.e., the fault). Generally it requires less total/differential stress to have movement along an existing fracture than forming a fracture, so if we sidestep the logistical impossibility from above, if we were able to do this, at best you've increased the stress necessary to reform the fault (compared to have slip on the fault) that you sealed, but if the stress exists, the rocks will just break again eventually. This also largely ignores the existence of extensive damage zones around faults (e.g., Kim et al., 2004). In detail, the fault planes themselves are surrounded by halos of "damaged" i.e., fractured and otherwise weakened, rock with the width of the damage zone being proportional to the amount displacement accommodated by a fault. If we're considering a large, plate boundary scale fault, the damage zone might be hundreds of meters to several kilometers wide. So in some hypothetical where we were able to "seal" the fault plane itself, the fault would likely just reorganize within the damage zone as this would be weaker than the "sealed" fault or intact rock outside the damage zone, assuming the stress still exists. Which brings us to our final point.

3. Faults are manifestations of differential motion between portions of the crust and upper mantle, driven by differential stress resultant from plate motion. If we assume that we could somehow overcome the logistical challenges in the first point, and even if we were able to maybe somehow "seal" the entire damage zone discussed in the second point, none of this changes the driving stresses. As a simple analogy, if you tear a piece of paper and then "seal" the rupture with some tape and then try to tear the paper again, it's not as though the paper won't just rip again (even if you do a great job with your tape and it doesn't reoccupy the same tear, some other part of the paper will tear instead). As long as a stress is being applied that overcomes the strength of a portion of the material, a fracture will form to accommodate the differential stress and motion. Thus, if we assumed we could "seal" faults, this wouldn't really do anything unless you somehow also stopped plate tectonics.

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> I went to Ireland and visited a beach. I took home a rock as an souvenir of my trip. I live in America, and I wonder, are the rocks in Ireland different from American rocks?

It depends on where you were in Ireland and, since you're dealing with a rock you picked up from a deposit of loose sediment, where in Ireland the particular rock you picked up came from. Like most places, Ireland has a variety of rocks of different ages and geologic histories that are exposed (e.g., the wiki page on the Geology of Ireland). Depending on where in Ireland your rock came from (and where in America you're comparing it to, as similarly, there are lots of different ages, compositions, and histories of rocks in North America), it might be quite different or it might be pretty much the same. For example, portions of what now is North America (i.e., Laurentia) and Ireland (i.e., Avalonia) were joined during the Caledonian Orogeny. There are formations (i.e., packages of rocks of the same age and similar lithology which represent deposition in a single largely continuous depositional environment in a particular area) which appear in New England and Ireland (and elsewhere), e.g., the Old Red Sandstone.

At a more basic (and slightly pedantic) level, it also depends on how specific you want to be and how you want to define "the same." Let's consider a sandstone from Ireland and one from America. If you keep it super shallow and stick with basic rock type, then for sure you can find the "same" rocks all over the world, i.e., a sandstone is a sandstone regardless of location. As you get more specific, things will narrow as you consider differences in grain size (e.g., coarse sandstones are not the same as medium sandstones) or details of composition (e.g., arkoses are not the same as quartz arenites). If you keep getting more specific, you could start considering do these two sandstones have the same age and source, i.e., do they represent effectively the same original deposit. All of these definitions of two rocks being the same would be appropriate depending on the context. For this last, most strict type of "sameness", let's consider the other part of your question.

> Like if I ran science tests, could the rock be determine it's not from America. Or all rocks, just rocks.

For simplicity, I'll keep my focus on sedimentary rocks, and then this would broadly fall under the umbrella of sediment provenance. There are a wide variety of characteristics of a sedimentary rocks (e.g., age populations of detrital minerals, sand composition, and a variety of geochemical proxies) that can be used to "fingerprint" the source of these rocks and thus establish individual sedimentary rocks as semi unique. Being able to identify a particular sedimentary rock through provenance analysis depends on the details of the rock in question, i.e., some may be more unique than others and easier to fingerprint. Because of plate tectonics, most landmasses have complicated histories where currently disparate bits may have been in close proximity (like the example with the Caledonian orogeny and the Old Red Sandstone), so it's not as though all Irish rocks will be distinctively Irish or something, but rather rocks of different ages will reflect the plate tectonic configurations and depositional environments at the time they were formed and thus will have "affinities" with rocks in different places.

Yeah I 'member being under the shower and apparently soaping myself three times because I forgot I'd just done that...

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No, Australia was separated from Asia during the glaciations while the parts of Indonesia homo erectus went to were contiguous to Asia.

There's no evidence homo erectus ever learned to build boats to cross to islands like Australia.

Hi!

No. There is loads of evidence of H. erectus and other earlier members of genus Homo making it to Indonesia and surrounding islands as you state (see: Trinil, Sangiran, H. floresiensis, etc.). However, there are no evidence of hominins other than H. sapiens found in Australia.

Keep in mind that Australia was not attached to mainland Eurasia. There were periods of time when Indonesia was accessible by foot. There is no evidence that H. erectus made boats.

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It depends what you use to determine speed. Body lengths are a way of comparing speed of different organisms. By this measure, the Southern California mite is the fastest with speeds in excess of 300 body lengths per second.

That would be like a human going about Mach 2.

What you’re describing sounds more like someone trying to prevent wear with a retainer as a guard more than actually used as a retainer. Not abuse and can be really important to protecting your teeth. Wear is more than just cosmetic when it’s a chronic thing that happens for a long time

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DON'T stop wearing your retainers. Wear them at least 3 or 4 night a week. I stopped wearing mine after my puppy got a hold of them, and figured my teeth were fine. My teeth then shifted SO GRADUALLY that I didn't really notice until a year later when I REALLY looked at my teeth and the damage was done. They're not horrible, but they're definitely not straight like they were, and my one side tooth bugs me now. I had new retainers made and wear them at least 3 nights a week and always will.

Isn’t there a discipline that uses a different term for “microorganism”? I don’t think it’s microbiologists, but maybe for a photographer, the term “microorganism” can denote anything that requires a macro or micro lens to properly observe.