Timed Scanning/Skimming Practice 7 - 4 Questions in 3 Minutes.

DIRECTIONS:
THE QUESTIONS IN THIS PRACTICE SET ARE ALL FACTUAL; THEY CAN BE ANSWERED BY MERELY SCANNING THE PASSAGE BELOW LOOKING FOR CLUE-WORDS FROM THE QUESTIONS.
IF IT IS YOUR STRATEGY TO READ THE QUESTIONS BEFORE READING THE PASSAGE YOU CAN DO THAT IN THIS ACTIVITY. JUST SCROLL TO THE BOTTOM OF THIS PAGE AND CLICK START NOW.
IF IT IS YOUR STRATEGY TO READ OR PREVIEW THE PASSAGE BEFORE LOOKING AT THE QUESTIONS, YOU MAY DO SO NOW.

If a meteor colliding with Earth caused the extinction of the dinosaurs, where was the point of impact? Only a bolide roughly the size of Mt. Everest could effect such a catastrophe; all known impact craters were too small to have been made by such a giant. In 1990 PEMEX, a Mexican oil company, announced that workers had discovered such a crater during off-shore drilling. Core samples and magnetic testing revealed that the area beneath Chixulub, Yucatan is the center of a 65 million year old crater with a diameter of 180 kilometers. This area is situated upon a bed of limestone, a carbon-rich rock that, once ignited, converts to explosive carbon-dioxide gas. Age, size, and composition all point to Chixulub as the point of impact for the massive bolide collision that radically changed the face of Earth.

Recent history offers an example of a bolide's destructive potential: the Tunguska Event. On June 30, 1908, a massive fireball exploded over Siberia with an explosive force equal to 2,000 times the power of an atom bomb. Reindeer grazing in this area were immediately incinerated and trees were knocked down and burned over and area of 2,150 square kilometers, roughly the area of Washington, DC. The bolide exploded before impacting with Earth and still the resulting shock waves were heard and recorded as far away as London, England. If this incident had occurred over a populated area it would have constituted the greatest natural disaster of recorded time.