Monday, May 23, 2011

Book Signing in Golden

Come hear Golden author
David Schey
Read from his book
Ancestors of Gods

Saturday, May 28th
Read, Write & Brew

Dave was a minerals exploration geologist who is currently working as a volunteer in the paleontology lab at the Denver Museum of Nature and Science.  His book talks about the science-religion conflict and takes place at an early American habitation site in the foothills southwest of Denver.

Read, Write & Brew
720 Golden Ridge Road
Unit D
303 945-7447
Read, Write & Brew is located in the Golden Ridge Shopping Center
Rt 6 at Heritage Road in Golden

Wednesday, May 4, 2011

Why We Believe What We Believe

For many of us, what we believe is primarily the same thing as what our parents believed. We have just accepted what we were told and never questioned it. This applies to the religion we currently hold, the political party to which we belong, and even, sometimes, the make of car we drive. Our parents taught us what they believed to be true because it is what their parents taught them. They were not trying to deceive us. They were simply telling us what they believed to be true.

So, how do we know what is true? I’m of the opinion that we are incapable of knowing what is absolutely true. For each of us, truth is relative. Who is right? How can a Republican sincerely believe one thing and a Democrat believe something quite different or a Lutheran sincerely believe one thing and a Catholic something else, each convinced they are right and the other is wrong?

The reason we cannot know absolute truth is because each of us perceive the world differently, and we perceive things differently because of the memories we have associated with that belief. If we are brought up a Lutheran, we have Lutheran memories – memories we built as we were growing up. Those memories tell us what is true  – Lutherans are going to Heaven and Catholics are going to Hell (or vice versa). The danger is that what we accept as true is stored in our memories and future decisions become influenced by them.

About a year ago, we were trying to sell an extra Blackberry phone that we had acquired. My wife advertised it on CraigsList and a gentleman called and came to our house to see it. At the time we had a full-grown Samoyed dog, one of the friendliest dogs you could know. When I answered the door, I invited the gentlemen in to see the phone. He started in the doorway until he saw our dog. At that point he froze and would not come in; I had to bring the phone outside to him. Perhaps, sometime in the past, he had had a bad experience with dogs. Perhaps one had bitten or mauled him; he was clearly frightened by the sight of our dog. My wife and I and our neighbors know that our dog would never hurt anyone. That was the truth as we saw it. This gentleman, however, had a different truth and he believed our dog was dangerous. Clearly the truth that we had about the dog and the truth that the gentleman had were quite different.

It is for this same reason that Republicans and Democrats or Lutherans and Catholics can believe that they are right and the other is wrong. It is because of the way we perceive the truth, or what is right. Consequently, it can be very difficult to change your own or someone else’s mind. First, you have to change the memories, replace the old memories with new ones. And, giving up old memories is very difficult to do. Changing someone else’s mind can be a long slow process. The idea is to get them to think they changed their mind on their own rather than you having any part in changing it. It is called education.

We need to be careful with what we allow to become our memories, of what we accept as truth. I like to think of our mind like we think about our bodies; we are what we put into it. If you eat junk food you will not have a healthy body and will increase your chances of suffering medical problems. If you allow junk into your mind, you will make faulty decisions. By junk I’m talking about junk science or pseudoscience. For example, if you have accepted homeopathy as a valid means of treating illness you may suffer the consequences.  In this regard, I like to think of tested medicine as being the better cure and science as offering the best method of finding absolute truth.

Tuesday, April 19, 2011

Extinction of Ice Age Mammals

It has recently been proposed that a comet or an asteroid may have exploded over northeastern North America around 12,900 years ago. The resulting fireball touched off immense wildfires over much of North America and sent debris into the atmosphere that settled as far away as Europe. A thousand year period of global cooling known as the Younger Dryas began about this same time and may have been the result of the bolide (comet or asteroid) explosion. Previously the Younger Dryas was thought to have resulted from the sudden influx into the Atlantic Ocean of fresh cold water from large glacial lakes that had been forming at the front of the retreating continental glaciation following the retreat of the ice sheet near the end of the last ice age. Perhaps the breakup of the ice was a result of the exploding bolide. 

The theory of an exploding bolide could explain other key events that happened around this same time period. In addition to the sudden mini-ice age recognized as the Younger Dryas, the distinctive Early American Clovis culture seems to have vanished at this time. Also a number of mammal species – mammoths, mastodons, giant ground sloths, giant beavers, saber-tooth cats, horses, and camels - went extinct about this same time. Much of the evidence for a bolide impact is found in a distinctive carbon-rich layer of sediment containing material indicating extraterrestrial origin. This sedimentary layer has been found at a number of Clovis habitation sites in North America. 

 Image Credit: from E.C, Pielou (1991)

However, more recently, the comet theory has met with increased skepticism. The main evidence cited by Firestone et al. (2007) in favor of the bolide theory is magnetic microspherules, carbon microspherules, fullerenes, a helium-3 anomaly, an iridium anomaly, a radiation anomaly, abundant charcoal and nanodiamonds. Haynes et al. (2010), however, argue that these anomalies are not indicative of extraterrestrial origin and use evidence of samples they collected from roof tops to demonstrate the source of anomalous values. Although Haynes et al. cannot support the bolide explosion and resulting extinctions, they admit that their evidence also does not preclude it.

Other extinction theories that have been proposed in the past include human overkill, climate change, and pandemic disease.

Paul Martin of the University of Arizona has been a champion of the overkill hypothesis. Martin’s hypothesis is that the extinction of many of the megafauna near the close of the ice age was the result of overkill by the Early Americans arriving in North America. There is evidence of massive kill sites in Canada and in the lower US where herds of animals such as buffalo were run over cliffs resulting in the death of many more animals than could be used to feed the people.

Climate change has also been proposed as a cause of the extinctions and an abrupt cooling period about 12,900 years ago, known as the Younger Dryas was mentioned above. When the North American ice cap had melted sufficiently to open up drainage of the massive lakes dammed behind the glaciation, it flowed out through the present Hudson Bay area into the North Atlantic. This inflow of water altered the ocean currents in the Atlantic and resulted in a cooling of the Northern Hemisphere.

Pandemic disease among the mega-mammal populations has also been proposed by Kathleen (2004), among others. The idea behind the pandemic disease is that the Early Americans brought a plague-like disease with them when they arrived in the new world that was transmitted to the mega-mammals, and it was this disease that caused the extinction.

For my novel, Ancestors of Gods, I liked the idea of a bolide striking the Earth, because that theory makes for a better story. In the end, however, it may have been a combination of factors that caused the extinctions. This is supported by the fact that the extinctions do not appear to be sudden or restricted to a certain time period. Instead the extinctions seem to have occurred over a period of time. Some of the last woolly mammoths survived on Wrangel Island off the northeast coast of Siberia until about 4000 years ago.


Pielou, E.C. (1991) After the Ice Age; The Return of Life to Glaciated North America; The University of Chicago Press; 366 pages.

Firestone RB, et al. (2007) Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling; Proc Natl Acad Sci USA, 104:16016–16021.

Haynes Jr. et al. (2010) The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact; March 2010, 107(9), 4010-4015.

Lyons, S. Kathleen, (2004) Was a ‘hyperdisease’ responsible for the late Pleisotcene megafaunal extinction?; Ecology Letters, Vol. y, Issue 9. 

Sunday, April 3, 2011

Migration Routes for the Early Americans

An article in the recent issue of Science magazine details findings at the Buttermilk Creek archaeological sites in Texas and discusses migration routes of Early Americans into North America. Findings at these Texas sites argue for pre-Clovis Early Americans in North America as early as 15,500 years ago.

During the last ice-age sea level was some 400 feet lower than it is today. The lower sea level exposed a land mass, Beringia, that stretched between Siberia and Alaska and was as much as 1000 miles wide. Most scientists think that Early Americans arrived in North and South America via this route.

The “Clovis-first” proponents believe that Early Americas arrived in the present lower 48 states of North America between 12,800 and 13,100 years ago. Another group of archaeologists believe that Early Americans crossed through Beringia earlier, as early as 40,000 years ago.

There were two general paths of migrations from Siberia into the lower parts of North America. If people were in the southern part of North America prior to about 15,000 years ago, they probably arrived by boat following the Pacific coast. Prior to that the continental ice sheet covered most of present day Canada and joined with the Cordilleran ice sheet that covered the Rocky Mountains out to the Pacific coast. The only migration route available at the time was the coastal route. The ancestors of the people who lived along Buttermilk Creek probably followed this route.

Image credit: Dixon, E. James (2000)

15,000 years ago the ice sheets began to retreat and, in the process, opened up an ice-free corridor along the eastern side of the Rocky Mountains. The “Clovis-first” proponents favor Early Americans arriving in the southern part of the continent via the ice-free corridor route.
Image credit: Dixon, E. James (2000)

Another theory, favored by Dennis Stanford of the Smithsonian Institution and Bruce Bradley of the University of Exeter, suggests that the Early Americans came to North America from Spain, following the edge of the North Atlantic ice cap. Stanford and Bradley’s main argument is that the Clovis points in the Americas appear very similar to the Solutrean points found in southern Europe (see figure below). Also, currently, the preponderance of Clovis sites appear to be located in the eastern US. Stanford and Bradley suggest that ice-age fisherman and hunters sailed to America in small boats made of animal skins about 18,000 years ago; similar to the boats used by Eskimos today to hunt whales and seals.

Evidence suggesting Clovis-age people used the ice-free corridor has been found in Alberta and British Columbia. Some evidence has also been found along the Pacific coast supporting the coastal route theory. However, there may be even more evidence that is now under water. Any possible evidence for the migration route from Europe would now be at the bottom of the Atlantic Ocean. 

There is good evidence of an Early American settlement at Monte Verde, Chile that date back to at least 12,500 years ago and possibly as much as 14,800 years ago. As additional study is being made, evidence supporting earlier arrivals of people into North and South America is increasing. Migrations from Siberia likely happened more than once and each may have followed different migration routes. However, studies of current native North Americans, focusing on language, dental structure, and genetics, pretty well demonstrate that their ancestors came to the Americas via Siberia. So far the evidence for European origins is lacking.

Waters, Michael R., et. al. (2011) “The Buttermilk Creek Complex and the Origins of Clovis at the Debra L. Friedkin Site, Texas”; Science 25 March 2011: Vol. 331 no. 6024 pp. 1599-1603

Dixon, E. James (2000) "Bones Boats & Bison; Archeology and the First Colonization of Western North America"; The University of New Mexico Press; 322p.

Mithen, Steven, (2003) “After the Ice”; Harvard University Press; 622 p.

Monday, March 14, 2011

Summary of Japan Earthquake in Terms of Plate Tectonics

In light of the earthquake and tsunami that hit Japan last Friday, I thought I would talk about the geology that helps explains what happened. While I was in graduate school, the theory of plate tectonics was hitting full stride. Many of the geology department’s special seminars at that time were presented by leading figures who were active in flushing out the details of the theory. 

The new theory of plate tectonics replaced the old continental drift theory that never gained widespread acceptance by the geological community. Continental drift recognized how the east coast of North and South America seemed to fit nicely into the west coast of Europe and Africa. However, the theory of continental drift proposed that the continents somehow were able to float or push through oceanic crust. No one knew how this might occur. How do you explain how rock can drift through other solid rock? However, some felt it was a good theory and they felt that eventually the scientists would discover the mechanism by which this could occur. 

During the late 1960s and early 1070s, the results of various studies began to come together in support of a new theory; one in which the continents were not drifting through the Earth’s crust, but that the continents were fixed to crustal plates that drifted over the Earth’s surface. According to plate tectonic theory, the Earth’s crust consists of approximately 30 rigid plates varying typically from about 10 miles thick for oceanic crust to about 120 miles thick for continental crust.

 Figure 1. The Earth’s Major Tectonic Plates (from USGS)

 There are three kinds of relative motion occurring between these tectonic plates - spreading centers (divergent), such as along mid-ocean ridges; transform faulting, where the plates are sliding past each other; and subduction zones (convergent), where one plate is being overridden by another plate. 

Figure 2.  The Three Types of Tectonic Plate Boundaries (from Rapid Uplift).

Some of the early studies that supported the theory of plate tectonic theory showed that new oceanic crust was being formed along oceanic ridges, such as the mid-Atlantic ridge. This was verified by the study of the age of the rock obtained by deep-sea drilling, at various distances from the ridge. The further away from the ridge, the older was the rock. Additional evidence that was being found about the same time dealt with the pattern of paleomagnetism*. On average, about every 200,000 years the Earth’s magnetic field reverses. The pattern of reversals can be seen in magnetic surveys perpendicular to the oceanic ridges. The reversal patterns on both sides of the oceanic ridge match and can be dated from the rocks that were cored and dated. The reversal patterns show the same pattern as the rock ages; the further one proceeds from the ridge the older the rock.

I like the analogy of an egg to describe plate tectonics. Imagine an egg in which the shell has been cracked into a number of pieces that are still attached to the egg.  Spreading centers occur where two of the egg shell fragments are being pulled away from each other. Perhaps you could think of the whites of the egg seeping up between the spreading shell fragments, sticking to the edges and hardening to form new shell. However, if this was the only mechanism, the size of the egg would slowly begin to increase. The size of Earth, however, has not been increasing in size. To negate this, there are other places on the egg where one shell is being overridden by another. This would be analogous to a subduction zone where one of the Earth’s plates is subducting or diving down under a plate that is overriding it. On other parts of the egg, one shell is simply sliding past another shell.

A short video demonstrates plate tectonics and shows the motions of the Earth's plates over the past 200 million years.

Japan is located above a subduction zone. The northern part of Japan is actually located on a part of the North American Plate (figure 1) that is overriding the Pacific Plate. The Pacific Plate is diving down and to the west under Japan. Friction along the plate boundary is not smooth and most of the time the rock on the two plates sticks together. When the forces between the differential motion of the two plates become strong enough, rupture between the two plates occur and the earth moves. This is when an earthquake occurs. In this latest earthquake in Japan the overriding plate is thought have been lifted as much as 30 feet. The uplifting sea floor also lifted the overlying column of ocean water. Gravity then caused the waters to flow westward toward Japan and eastward toward North America. Although this animation was created to show what happened during Sumatra earthquake and tsunami of 2004, the same mechanism caused the devastation that happened in Japan.

* paleomagnetism – Paleomagnetism is the study of the magnetism left in rock by the Earth’s magnetic field when the rock is formed. As molten volcanic rock rises along the mid-ocean ridges, the iron in the rock aligns with the Earth’s magnetic field and is frozen into the rock as it cools and hardens

Other references:
  1.  Rapid Uplift Blog by Suyrat Kher.
  2.  Japan earthquake: The Explainer, Chris Rowan blog.
  3.  Plate Tectonic Animations, Paleomap Project, Christopher R. Scotese.
  4.  Observe animations of processes that occur along plate boundaries, Exploring Earth Visualization, McDougal Littell.