Sylas, great post. Many others have explained the same thing in more or less the same terms, but I guess the antagonists on this thread are not happy with the answer so they keep fishing around for one they feel comfortable with. Sorry, but individual comfort level with evidence/fact is of no consequence in science. The evidences/facts must speak objectively and not be tied to any subjective opinions. (How scientific findings are applied to civic situations can be argued over subjectively, though.)
Anyway, I teach uniformitarianism in the same unit with fossils, principle of superposition and geologic time. Our Earth Science text--Glencoe 1997--explains uniformitarianism as the processes occurring today also occurred in the past. The text I used for my Intro to Earth Science Education college course--Tarbuck, I think--also explained uniformitarianism in the same way. He also said that this does not mean that catastrophes cannot occur. They do. After talking with the other two earth science teachers at my school, I found that they teach uniformitarianism the same way--present events also happenned in the past and the present is the key to the past. As a group, we also make sure our students know that catastrophes have happenned and continue to happen, but that does not dismiss the fact that gravity has always been gravity and erosion has always occurred through the actions of gravity, water, wind, and energy, and mountains being formed today--Kilahuea and the Himalayas, for example--have always been formed in certain ways, etc.
So what is the big deal?
ps...if you haven't already, sign the petition on the ohio thread in this forum. Good science education needs to stay that way.
We teach uniformitarianism as it is understood in its modern form. It is basically a given, i.e. of course processes happening now also happened in the past. We also talked about continental drift. However, both are talked about in a historical context and how they led toward a more modern understanding of geology, such as the theory of plate tectonics.
quote:They will discover that while certain properties of the earth system may fluctuate on short or long time scales, the earth system will generally stay within a certain narrow range for millions of years. This long-term stability can be understood through the working of planetary geochemical cycles and the feedback processes that help to maintain or modify those cycles.
This comes from the NSES web site. Does anyone disagree with this?
Re: Question about Public School Geology Text Books
Exact exerpt from Glencoe Earth Science 1997--
quote:Uniformitarianism Before radiometric dating was available, many people had estimated the age of Earth to be only a few thousand years old. But in the 1700's, Scottish scientist James Hutton estimated that Earth was much older. He used the principle of uniformitarianism. This principle states that Earth processes occurring today are similar to those that occurred in the past. He observed that the processes that changed the rocks and land around him were very slow, and he inferred that they had been just as slow throughout Earth's history. Hutton hypothesized that it took much longer than a few thousand years to form the layers of rock around him and to erode mountains that once towered kilometers high. John Playfair advanced Hutton's theories, but an English geologist, Sir Charles Lyell, is given the most credit for advancing uniformitarianism.
From Glencoe Earth Science 2002--
quote:The principle of uniformitarianism states that the processes occurring today have been occurring since Earth formed. Only the rate, intensity, and scale with which they occur have changed.
In both texts, the PofU is talked about in a historical context to show that "As late as the turn of the nineteenth century, the majority of the world believed that Earth was only about 6000 years old." Something about Ussher, then Hutton, and finally what I quoted in the box above. The paragraph ends with an example talking about how what causes the waves of the ocean has not changed since the oceans formed. It also talks about the distribution of sediment occurring in the same way it does now. (Glencoe Earth Science 2002)
So modern geology has outgrown the need for a principle that states the obvious. OK, but we are talking about teaching not just science, but history as well. I tell the kids what the principle of uniformatarianism states and that it is pretty much a given now, but back when it was first thought of, it was a new way of thinking. I say the same things in biology when I talk about the Cell Theory. From Lucretius in 55 bce to Needham and Spallanzani in the mid-1700's to Pasteur's flasks in 1861. Uniformitarianism might sound like it is proposing that things happen uniformly throughout history, but that is not what we teach. If that makes me a lousy teacher, so be it. You have any better suggestions, Tamara?
Percy, I don't think we teach it as being part of the modern lexicon. If you want to say something about it, we talk about it when we talk about relative and radiometric dating. It is actually skimmed over with only one question on a worksheet for the students to answer--What does the principle of uniformitarianism state? I don't think we even test it!