When Did Humans Reach the Americas?

This question has been simmering in the back of my mind for decades. I’ve given panels on it at science fiction conventions, and I’ve written blogs on the subject before, too. I believe the last blog I wrote about it theorized that an ice-free channel through the North American glaciers of the last ice age opened up about 14,000 years ago. And therefore people who had crossed the Bering landbridge sometime before that were finally able to leave Alaska and find their way south to the plains of central North America. And from there, they could have gone on to populate all the rest of North America, Central America and South America.

But even that might not be right.

The other night, we watched a documentary about fossilized footprints in the White Sands National Park in New Mexico. Although the area is a desert now, during the last ice age, it housed a large lake. The fossilized footprints recorded the presence of Columbian mammoths, great ground sloths, North American camels and horses. And among all those footprints, it is not at all unusual to find lots of human footprints.

Scientists have to work fast to learn all they can from these footprints, because as soon as they are revealed by the wind blowing the sand away, the blowing sand starts to erode the footprints away. For these are not the usual fossils that have been turned into stone. Some of the footprints are impressions in the sand, that had been filled with silt that was finer than the sand around them. Others are outlined with bulging sand indicating the weight of the animal. All of them dried out when the lake dried up, and little has happened to the area to disturb them. Except the blowing wind.

A number of scientists work the site each year, and I was left with the impression that each year presents a new batch of footprints, at a slightly lower level than the year before.

One year—and it didn’t say what year it was—a pair of scientists who are experts at radio-carbon dating dug a trench in the sand, going down through several layers of human footprints. But you can’t radio-carbon date sand; you can only radio-carbon date organic material, like plants or animals. By examining the layers between the human footprints, they were able to find organic material, such as seeds or pollen. They packaged up a number of these samples and took them back to their lab in Denver to date them.

Two years later, the narrator visited them in their lab to ask what kind of dates they had gotten from their samples. They said they had gotten dates between 21,000 and 23,000 years ago! That would have been long before the ice-free trail through the glaciers had opened up!

At the very end of the show, the narrator was talking to another scientist, and wondered how humans could have gotten so far south before the glaciers had started to melt. The anthropologist said they had probably followed the Pacific coastline, starting in Alaska and working their way south. But, he pointed out, the sea level was much lower at that time (as much as 400 feet lower), with so much water tied up in the glaciers, so any settlements they might have established would be underwater now. He suggested we should be doing more diving along the coastline to find them.

Okay. Who still thinks that ancient alien visitors brought a herd of humans to the Americas? (This was the last suggestion I made when I gave this talk at conventions.)

Siderian & Rhyacian Periods

 

Siderian Period

There are 4 periods in the Paleoproterozoic Era, the first being the Siderian Period. This period lasted from 2,500 to 2,300 million years ago.

Early in this period is when banded iron formations peaked. As I explained before, cyanobacteria produced waste oxygen, which initially combined with iron that was in the sea, forming magnetite (Fe3O4), an iron oxide, in a crystal structure rock. This process removed iron from the oceans, presumably turning the greenish water clear.

Then, with no remaining iron in the sea to serve as an oxygen sink, the oxygen escaped the ocean and built up the oxygen level in the atmosphere. This led to the oxygen catastrophe, wherein a great deal of the life then existing on the Earth was wiped out because they could not tolerate such high levels of oxygen.

Some geologists believe the high level of oxygen also triggered the Huronian glaciation. This glaciation started in mid-Siderian (2,400 million years ago) and extended into the next period, lasting until 2,100 million years ago. It was apparently caused when free oxygen combined with the methane in the atmosphere to form carbon dioxide and water, which do not retain heat as well as methane does. With far less of this greenhouse gas in the atmosphere, a great chilling took place, also known as the Huronian glaciation. I don’t know if the entire planet froze, and the article stated that this glaciation caused a mass extinction. I’m waiting for a geologist I know to clarify whether there were 2 mass extinctions so close together, or just one, with both the presence of oxygen and the cooling temperatures to blame.

 

Rhyacian Period

The Rhyacian Period is the 2nd geologic period in the Paleoproterozoic era. It lasted from 2,300 to 2,050 million years ago. And that is just about all the wikipedia article had to say on the subject. Oh, there were a bunch of rock formations created, and the Huronian glaciation lasted 100 million years, but that still leaves 150 million years at the end of the period during which, apparently, absolutely nothing of note happened.

Oof! What was the tipping point that caused the end of the glaciation? For that matter, did it cover the entire Earth? Was there an explosion of new species afterwards?

Maybe they don’t know. What about theories? Doesn’t anybody have any theories? Well, without sitting my geologist friend down and picking his brain clean, I guess that’s as far as I can go with this period. Maybe the next 2 period of the Paleoproterozoic Era will have more meat to them.

 

https://en.wikipedia.org/wiki/Siderian#:~:text=The%20Siderian%20Period%20(%20%2Fsa%C9%AA,these%20dates%20are%20defined%20chronometrically.

https://en.wikipedia.org/wiki/Rhyacian

Poor Science or Poor Writing

The other day, my husband and I watched a movie we’d never heard of. The setting of the story was that Earth had been in winter for the past 300 years, and it would continue for thousands of years. The only humans that still existed lived 10 kilometers under the surface, where they used geothermal energy as their power source. They had created a race of ‘humans’ to do their work for them, including sex workers, but nobody ever indicated what type of work this ‘inferior’ race did, except for the one sex worker.

Hubby had difficulty with Arizona being covered in snow and ice, with daytime temperatures of -60° F. In the latest ice age, the glaciers never reached the sw states. To me, that said the the earth was not just in an ice age, but had entered a ‘snowball earth’ ice age, where the entire globe is frozen.

How did the ice age winter begin? The characters gave 2 theories, but didn’t know which was right. The first theory was that an asteroid had struck the earth, throwing up so much dust and debris into the atmosphere that most of the sunlight couldn’t get to the ground. The second theory was that it was a bomb that threw up all that dust and debris.

Okay, yes, a lot of dust and debris in the atmosphere can reflect enough sunlight to produce some very chilly results. Large volcanos can produce enough dust to chill the entire globe as the dust rides through the atmosphere. BUT, such dust doesn’t stay in the atmosphere for hundreds or thousands of years.

What about the asteroid that ‘killed the dinosaurs’? you may ask. Yes, that threw up a lot of dust and debris. But what killed so much of the flora and fauna was the firestorm produced by the heat released when the asteroid hit. Think of it as a huge explosion, so hot the heat wave raced around the globe, burning almost everything it touched. There may have been a long winter afterwards, but all that dust and stuff did settle out in a fairly short amount of time.

The plot was that a squad of ‘normal’ military-type humans had to go out into the world to track down a renegade ‘inferior’ made human. The squad's DNA was changed to allow them to survive in the far-below-zero temperatures, but that would only last for 48 hours. I had a little trouble accepting that, but... okay, let’s see what they do with it.

The scene that got me was right after they arrived on the surface. It had been stated that ‘all the animals’ were gone. But what they see right after they arrive on the surface was a man fishing. He had chopped a hole in the top of a small rivulet of water racing over the snow/ice, and had actually caught a fish, but seeing that he was going to be interrupted, he put the fish back.

I really couldn’t accept that. If all the animals had died, where did this fish come from? Okay, maybe they were mistaken. But at the temperatures they were talking about, I would expect that little rivulet to be frozen solid, and the fish with it.

It didn’t help that long after the main character had been on the surface for 48 hours, the main character was still chasing the renegade, with his head bare and no gloves. Frostbite was completely ignored.

It was not a good movie. If you are going to change the rules of life (daytime temperatures of -60F), then you (the writer) have to follow those new rules. And it is easy to have characters who don’t know what happened to end the civilization we (the audience) are familiar with. It’s easy for the writer, but it’s not satisfying to the audience.

The Sky is Falling

If you follow me on facebook, you may have noticed that I have shared many articles on climate change and that I have started using the comment, “The Sky is Falling.”

It seemed more appropriate than saying, “The Boy Cried Wolf.” In that story, the boy is lying, only looking to introduce some excitement into his own life, without regard for the consequences.

Chicken Little, on the other hand, was telling the truth, as best he knew it. Something (a raindrop) had come down from the sky and hit him. He had never experienced anything like that before, so the logical conclusion was that something terrible was happening, the sky was falling! Chicken Little ran around the farmyard squawking his terrible news, trying to warn all the other farm critters.

Even that doesn’t exactly fit the problem of climate change. Chicken Little was very young and inexperienced. But it’s scientists who have been trying to warn the world’s population that the climate was changing far quicker than it should. They have lots of experience at studying climate and how it has changed in the past, and they have a pretty darn good idea where it’s headed.

In the past week, I have read several articles concerning the number and severity of heatwaves that have been happening around the world. Not only has the world been having more of them, not only have they broken records for daytime high temperatures, they’ve broken records for the highest low temperatures as well. That means that after a sweltering day, you don’t get much relief during the night, because the heat that has accumulated all day doesn’t dissipate fast enough.

I think Europe has already broken several summer records during a heatwave in June of this year. There’s no guarantee they won’t have another later this summer. Or this fall, or... whenever. A heatwave can happen at any time on the calendar, because it is a comparison between the present and what has been ‘normal’ previously.

The scientists don’t ‘think’ any particular place will start having a heatwave every year. But it could happen. After all, they wanted us to keep the warming of the Earth to 2°C or less. What are they saying now, that it’s officially reached a warming of 1.8°C? But in Europe, the temperatures reached +4 to +8°C over ‘normal’.

I don’t know about you, but I don’t get much done when the temperature gets to 95°F. I sure don’t want it to consistently reach 123°F. Or higher.

Maybe Chicken Little isn’t the best story for me to quote to try to get my point across, but it’s the one I can remember as the summer heat settles in. So I’ll keep squawking my warning and hope somebody is listening, because...

The sky is falling.

What is This World Coming to? 7

And we are back to water. It seems only fitting, since the globe is mostly covered by it.

As I was looking over information on Central America, one of my hard-copy magazines - Popular Science - had an entire issue on water. Including an article on the sudden and sustained lack of water in Colombia in the northern part of South America.

The northern part of South America is also definitely in the tropics, because that area straddles the Equator, and the tropics is generally 30° north to 30° south of the equator. That’s latitude degrees, not temperature degrees.

Colombia is also quite mountainous, but that doesn’t mean their water supply is assured. The article spoke of one city sitting in the heights below a ski resort. Until recently, that resort could exist because of a glacier that sat atop the mountain. That glacier also was the source of the water used by the city.

Guess what. That glacier is gone now. Not just receding, like so many glaciers are, it is GONE.

No more skiing on that mountain, no more water for that city. Now the water officials load up what water is available into tank trucks and deliver it around the area. When the truck pulls up and stops, everybody runs for whatever they have that will hold water; pots, barrels, bottles and jars. They may go home and empty those items into their sinks or bathtub and run back to see if the truck is still there. If it is, they fill their pots, barrels and jars again.

They don’t know how long it will be before the truck arrives to deliver more water, so they have to be stingy with every drop. It is all they have for cooking and possibly a sponge bath. In the meantime, they listen for notices from the government as to when the water in their taps may be turned on for a limited time.

At one point, the author was with a woman who had stayed home from work that afternoon. The water was supposed to be turned on in the pipes for 3 hours, and she wanted to get some laundry done. But the water never came from her pipes that afternoon. No laundry got done.

Did all the women in the city stay home that afternoon, hoping to get some laundry done?

The article ended with a brief mention of another Colombian city on another mountain, also depending on the mountain-top glacier for its water supply. That glacier is visibly shrunken, smaller than anybody has ever seen it before.

Perhaps they’ll figure out another source for water. The article didn’t mention any attempts to look, to figure something out. Everybody - even the water officials - just kept saying, “The rains will come.”

What are we, ostriches? Refusing to acknowledge a problem will not make it magically go away!

This is a depressing subject, and not the type I would usually spend time on trying to spin into an entertaining novel. I suffer from chronic depression and just found an anti-depressant that actually works for me. I don’t know if I’m done researching this subject or not... my constant companion - depression - keeps telling me to stick my head in the sand and think of pretty things. But the story for the novel is beginning to take shape in my head. I think I’ll start thinking out scenes and where they would go, and speak of other things in this blog for a while. If I need to, I can still do more research.

So, next time, the subject will be... Oh, who knows? Whatever I find interesting between now and then.