Which is the purpose of this article?

the barringer meteorite crater

the sky above the high plateaus of arizona fills with a blazing ball of fire. the air thins, and the ground trembles. daylight is replaced by a blinding flash of flames, and an ear-splitting howl roars across the land. a 150-foot long meteorite smashes into the ground, creating an immense crater. everything within a 100-mile radius of the impact instantly vaporizes along with the meteorite. within seconds, the landscape is changed forever.

does this sound like a scene from a summer movie? actually, it describes a real event that took place near flagstaff, arizona, 50,000 years ago. the hole created by the meteorite's impact, known as the barringer meteorite crater, can still be seen today. it is one mile wide and over 550 feet deep—20 football games could be played at the same time on its floor, and more than 2 million people could watch from its sloping sides.

however, when scientists first discovered the crater, they weren't sure if it had been created by a meteorite or by volcanic activity. in 1891, a geologist named grove k. gilbert began studying the inner regions of the crater and became confused for two reasons. first, he did not find any evidence of a meteorite in the crater itself. second, his instruments did not detect the presence of iron, a substance found in meteorites. gilbert concluded that some sort of volcanic explosion must have created the enormous crater.

ten years later, a mining engineer named daniel m. barringer heard about the crater. interested in using the area for mining ventures, he began exploring the land around the crater. he discovered that the surrounding plains contained large quantities of meteoritic iron. he also found huge boulders, some the size of houses, scattered around the crater. after reviewing gilbert's findings, barringer realized that they might be invalid when compared to these new discoveries. barringer searched the area for signs of volcanic rock. when he found no evidence of any past volcanic activity, he concluded that a meteorite had, in fact, created the crater.

convinced that gilbert must have missed meteoritic iron deposits beneath the surface, barringer began to mine the crater. this venture lasted for 27 years, but it produced nothing. however, his hard work laid the foundation for future scientists, who now believe that the meteorite disintegrated on impact because of the immense heat that it created. they have concluded that the meteorite's impact was equal to the explosion of 20 million tons of dynamite. this explains why the iron was sprayed across the plains and not deposited in the crater.

barringer's family still owns the land surrounding the barringer meteorite crater. a popular tourist attraction, the crater is used by nasa to train astronauts because its terrain resembles the surface of the moon. in fact, scientists now conclude that meteorites also created the many craters covering the moon's surface. they think that the holes and crevices, which create the appearance of a "man in the moon," are actually a series of impact sites.

today, scientists continue to study meteorites and craters. they believe that tiny meteorites, weighing less than a pound each, hit earth thousands of times a year. they have also identified over 150 craters as large as the barringer meteorite crater. in addition, scientists are studying several mysterious events, such as a blast that cleared an area of the siberian forest equal to the size of rhode island. could this have been the result of a meteorite? can people expect to witness a similar event in the near future? today, we have the technology that scientists predict when, where, and how these meteorites might fall.

a. to explain the effects of the impact of a meteorite
b. to demonstrate a lesson about the importance of scientific research
c. to describe new technology that scientists use to study meteorites