Imagine you are standing in a farm field in central Illinois. The land is so flat you can see for miles and miles. On a clear day, you might see a grain silo 20 miles away. You might think to yourself, it sure is flat around here. If you drive one hundred miles to the south, the landscape changes. In southern Illinois, there are rolling hills. Why do you think this is? What could have caused these features? There are no big rivers that may have eroded and deposited this material. The ground is capable of supporting grass and trees, so wind erosion would not explain it. To answer the question, you need to go back 12,000 years. Around 12,000 years ago, a giant ice sheet covered much of the Midwest United States. Springfield, Illinois, was covered by over a mile of ice. Its hard to imagine a mile thick sheet of ice. The massive ice sheet, called a glacier, caused the features on the land you see today. Where did glaciers go? Where can you see them today? Glaciers are masses of flowing ice.

How big were the glaciers?

(CNN) -- Argentina's star-studded line-up began their World Cup campaign with a 1-0 victory over Nigeria in their Group B opener in Johannesburg on Saturday. A goal from defender Gabriel Heinze after six minutes was all that separated the two teams after an inspired display from Nigeria goalkeeper Vincent Enyeama. But South Korea ended the day on top of the group following a 2-0 victory over Greece in Port Elizabeth earlier on Saturday. Goals from Lee Jung-Soo and Park Ji-Sung gave the 2002 semifinalists a comfortable win over the 2008 European cvhampions. Argentina 1-0 Nigeria Enyeama could do little to stop Heinze's powerful early header from a Juan Sebastian Veron corner, but he kept his team alive with a string of acrobatic saves to deny World Player of the Year Lionel Messi. Diego Maradona was delighted to secure his first victory as a World Cup coach, but critical of his strikers for failing to make the game safe. "When you don't kill things off in front of goal you can pay a heavy price. They almost got a draw -- we missed loads of chances," Maradona told AFP. "Players such as Leo Messi and Higuain knocked in around 60 goals last season between them, yet today it was almost as if they couldn't set their sights on goal. "But the win means we can be calm -- we are in the right track."

Who did Argentina play on the opening game?

On a busy Friday morning in Manhattan, nine pedestrians suffered bullet or fragment wounds after police unleashed a hail of gunfire at a man wielding a .45 caliber pistol who had just killed a former co-worker. The officers unloaded 16 rounds in the shadow of the Empire State Building at a disgruntled former apparel designer, killing him after he engaged in a gunbattle with police, authorities said. Three passersby sustained direct gunshot wounds, while the remaining six were hit by fragments, according to New York Police Commissioner Ray Kelly. All injuries were caused by police, he said Saturday. One officer shot nine rounds and another shot seven. Police identified the gunman as Jeffrey Johnson, 58, who was apparently laid off from his job as a designer of women's accessories at Hazan Import Co. last year. Johnson, who served in the U.S. Coast Guard in the mid-1970s, had two rounds left in his pistol. It holds eight, Kelly said. Police identified the slain co-worker as Steven Ercolino, 41, who had apparently filed a prior complaint against his assailant, claiming that he thought Johnson would eventually try to kill him. Both men had filed harassment complaints against each other in April 2011, Kelly added. Ercolino was listed as a vice president of sales at Hazan Import Corp., according to his LinkedIn profile. "It's not something that should happen to a loving person like that," said his brother, Paul. "He's going to be so missed by everybody. He was a light of so many lives."
What was the age difference between Jeffrey Johnson and Steven Ercolino at the time of Steven Ercolino's death?