paragraph about earth's age using 2 pieces of evidence to supporting the age of the earth and explain how the evidence supports how old the earth is
Answers
Explanation:
SCIENTIFIC AGE OF THE EARTH
Before analyzing the arguments advanced by creation “scientists” for a very young Earth, I here summarize briefly the evidence that has convinced scientists that the Earth is 4.5 to 4.6 billion years old.
There can be no doubt about the Earth’s antiquity; the evidence is abundant, conclusive, and readily available to all who care to examine it. The best evidence is contained in the Earth’s incomplete and complex but accurate stratigraphic record — a record that has been the subject of nearly two centuries of study. Slowly and painstakingly, geologists have assembled this record into the generalized geologic time scale shown in Figure 1. This was done by observing the relative age sequence of rock units in a given area and determining, from stratigraphic relations, which rock units are younger, which are older, and what assemblages of fossils are contained in each unit. Using fossils to correlate from area to area, geologists have been able to work out a relative worldwide order of rock formations and to divide the rock record and geologic time into the eras, periods, and epochs shown in Figure 1. The last modification to the geologic time scale of Figure 1 was in the 1930s, before radiometric dating was fully developed, when the Oligocene Epoch was inserted between the Eocene and the Miocene.
Although early stratigraphers could determine the relative order of rock units and fossils, they could only estimate the lengths of time involved by observing the rates of present geologic processes and comparing the rocks produced by those processes with those preserved in the stratigraphic record. With the development of modern radiometric dating methods in the late 1940s and 1950s, it was possible for the first time not only to measure the lengths of the eras, periods, and epochs but also to check the relative order of these geologic time units. Radiometric dating verified that the relative time scale determined by stratigraphers and paleontologists (Figure 1) is absolutely correct, a result that could only have been obtained if both the relative time scale and radiometric dating methods were correct.
The abundance and variety of fossils in Phanerozoic rocks have allowed geologists to decipher in considerable detail the past 600 million years or so of the Earth’s history. In Precambrian rocks, however, fossils are rare; thus, the geologic record of this important part of the Earth’s history has been especially difficult to decipher. Nonetheless, stratigraphy and radiometric dating of Precambrian rocks have clearly demonstrated that the history of the Earth extends billions of years into the past.
Radiometric dating has not been applied to just a few selected rocks from the geologic record. Literally many tens of thousands of radiometric age measurements are documented in the scientific literature. Since beginning operation in the early 1960s, the Geochronology laboratories of the U. S. Geological Survey in Menlo Park, California, have alone produced more than 20,000 K-Ar, Rb-Sr, and 14C ages. Add to this number the age measurements made by from 50 to 100 other laboratories worldwide, and it is easy to see that the number of radiometric ages produced over the past two to three decades and published in the scientific literature must easily exceed 100,000. Taken as a whole, these data clearly prove that the Earth’s history extends backward from the present to at least 3.8 billion years into the past.
A particularly fascinating question about the history of the Earth is “When did the Earth begin?” The answer to this question was provided by radiometric dating and is now known to within a few percent.
Three basic approaches are used to determine the age of the Earth. The first is to search for and date the oldest rocks exposed on the surface of the Earth. These oldest rocks are metamorphic rocks with earlier but now erased histories, so the ages obtained in this way are minimum ages for the Earth. Because the Earth formed as part of the Solar System, a second approach is to date extraterrestrial objects, i.e., meteorites and samples from the Moon. Many of these samples have not had so intense nor so complex histories as the oldest Earth rocks, and they commonly record events nearer or equal to the time of formation of the planets. The third approach, and the one that scientists think gives the most accurate age for the Earth, the other planets, and the Solar System, is to determine model lead ages for the Earth, the Moon, and meteorites. This method is thought to represent the time when lead isotopes were last homogeneously distributed throughout the Solar System and, thus, the time that the planetary bodies were segregated into discrete chemical systems. The results from these methods indicate that the Earth, meteorites, the Moon, and, by inference, the entire Solar System are 4.5 to 4.6 billion years old.