He has written some 30 books on dinosaurs and paleobiology, ranging from professional tomes to popular kids’ books. Learn the facts in Evolution 101, browse the resource library, read about evolution in the news, or discover a wealth of materials to help educate others about evolution and related concepts—it’s all right here!
The methods are all based on radioactive decay: The first radiometric dates, generated about 1920, showed that the Earth was hundreds of millions, or billions, of years old.Since then, geologists have made many tens of thousands of radiometric age determinations, and they have refined the earlier estimates.These demonstrate that, of course, we do not know everything (and clearly never will), but we know enough.Today, innovative techniques provide further confirmation and understanding of the history of life.Repeated recalibrations and retests, using ever more sophisticated techniques and equipment, cannot shift that date. With modern, extremely precise, methods, error bars are often only 1% or so.
The fossil record is fundamental to an understanding of evolution.
Fossils document the order of appearance of groups and they tell us about some of the amazing plants and animals that died out long ago.
Fossils can also show us how major crises, such as mass extinctions, happened, and how life recovered after them.
I intend it to be a mishmash of lessons, exercises and the occasional opinionated rant about the English language.
This post looks at non-defining relative clauses, also known as non-restrictive relative clauses, and a couple of very similar structures: sentential relative clauses and connective or coordinate relative clauses.
A key point is that it is no longer necessary simply to accept one chemical determination of a rock’s age.