Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.
Mountains have been built and eroded, continents and oceans have moved great distances, and the Earth has fluctuated from being extremely cold and almost completely covered with ice to being very warm and ice-free.
For example, based on the primate fossil record, scientists know that living primates evolved from fossil primates and that this evolutionary history took tens of millions of years.
By comparing fossils of different primate species, scientists can examine how features changed and how primates evolved through time.
There are two techniques for dating in archaeological sites: relative and absolute dating.
Research teams from the United States, the Soviet Union, Denmark, and France have bored holes over a mile deep into the ice near the poles and removed samples for analysis in their laboratories.The Third FAO/IAEA International Conference on Area-wide Management of Insect Pests: Integrating the Sterile Insect and Related Nuclear and Other Techniques is taking place this week in Vienna, Austria, to discuss new developments, trends and challenges related to insect pest management.The conference is part of the efforts of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture to assist Member States address the rapidly evolving field of insect pest management. View Video » Vets in Africa Help Prevent Spread of Ebola and Other Zoonotic Diseases.Aside from the fascination with salvaging several vintage aircraft for parts and movie rights, the fact that these aircraft were buried so deeply in such a short time focuses attention on the time scales used to estimate the chronologies of ice.If the aircraft were buried under about 250 feet of ice and snow in about 50 years, this means the ice sheet has been accumulating at an average rate of five feet per year.When it comes to dating archaeological samples, several timescale problems arise.For example, Christian time counts the birth of Christ as the beginning, AD 1 (Anno Domini); everything that occurred before Christ is counted backwards from AD as BC (Before Christ).The Greeks consider the first Olympic Games as the beginning or 776 BC.The Muslims count the Prophet’s departure from Mecca, or the Hegira, as their beginning at AD 662.The IAEA, in partnership with the Food and Agriculture Organization of the United Nations (FAO), is providing expertise and equipment to help countries use nuclear-derived techniques to detect zoonotic diseases and respond to them.Read More » At the Mexico-Guatemala border, the sterile insect technique halts the northward march of medflies since 1982.Based on flow models, the variation of oxygen isotopes, the concentration of carbon dioxide in trapped air bubbles, the presence of oxygen isotopes, acid concentrations, and particulates, they believe the lowest layers of the ice sheets were laid down over 160,000 years ago.Annual oscillations of such quantities are often evident in the record. Do they cause a problem for the recent-creation model of earth history? This article will show that the great ages reported for the bottom layers of ice sheets depend on assumed models of past climate and are not the result of direct counting of layers.The Greenland ice sheet averages almost 4000 feet thick.