Fossils can be used to match up rock layers. As organisms change over time, they look different. Older fossils will look different than younger fossils. Some organisms only survived for a short time before going extinct. Knowing what organisms looked like at certain times also helps date rock layers. Some fossils are better than others for this use. The fossils that are very distinct at certain times of Earths history are called index fossils. Index fossils are commonly used to match rock layers. You can see how this works in Figure 2.30. If two rock layers have the same index fossils, then they're probably about the same age.

Question: "How are index fossils used?"

Response: "They are collectable items"

A: no

In chapters 3 and 4 we described how the U.S. government adjusted its existing agencies and capacities to address the emerging threat from Usama Bin Laden and his associates. After the August 1998 bombings of the American embassies in Kenya and Tanzania, President Bill Clinton and his chief aides explored ways of getting Bin Laden expelled from Afghanistan or possibly capturing or even killing him. Although disruption efforts around the world had achieved some successes, the core of Bin Laden's organization remained intact. President Clinton was deeply concerned about Bin Laden. He and his national security advisor, Samuel "Sandy" Berger, ensured they had a special daily pipeline of reports feeding them the latest updates on Bin Laden's reported location. In public, President Clinton spoke repeatedly about the threat of terrorism, referring to terrorist training camps but saying little about Bin Laden and nothing about al Qaeda. He explained to us that this was deliberate-intended to avoid enhancing Bin Laden's stature by giving him unnecessary publicity. His speeches focused especially on the danger of nonstate actors and of chemical and biological weapons. As the millennium approached, the most publicized worries were not about terrorism but about computer breakdowns-the Y2K scare. Some government officials were concerned that terrorists would take advantage of such breakdowns. On November 30, 1999, Jordanian intelligence intercepted a telephone call between Abu Zubaydah, a longtime ally of Bin Laden, and Khadr Abu Hoshar, a Palestinian extremist. Abu Zubaydah said, "The time for training is over." Suspecting that this was a signal for Abu Hoshar to commence a terrorist operation, Jordanian police arrested Abu Hoshar and 15 others and informed Washington. One of the 16, Raed Hijazi, had been born in California to Palestinian parents; after spending his childhood in the Middle East, he had returned to northern California, taken refuge in extremist Islamist beliefs, and then made his way to Abu Zubaydah's Khaldan camp in Afghanistan, where he learned the fundamentals of guerrilla warfare. He and his younger brother had been recruited by Abu Hoshar into a loosely knit plot to attack Jewish and American targets in Jordan. After late 1996, when Abu Hoshar was arrested and jailed, Hijazi moved back to the United States, worked as a cabdriver in Boston, and sent money back to his fellow plotters. After Abu Hoshar's release, Hijazi shuttled between Boston and Jordan gathering money and supplies. With Abu Hoshar, he recruited inTurkey and Syria as well as Jordan; with Abu Zubaydah's assistance, Abu Hoshar sent these recruits to Afghanistan for training.

Question: "What was the concern of some officials when most people were concerned about computer breakdowns with Y2K?"

Response: "They were worried that terrorist would take advantage of breakdowns"

A: yes

Joe's parents are farmers and they have a huge farm with cows, chickens, and ducks. Joe loves the farm and all the things he gets to play around and play on. One day, Joe's father told him not to get near a tractor that was sitting in the field. His father was worried that Joe would climb on it and hurt himself. Joe went out to the field and was feeding the horses and cows. When he was done, he saw the tractor his father told him not to get near. He knew that climbing on the tractor wouldn't hurt anything, so he did. He climbed on to the seat and sat there. Then, he pretended he was his father and pretended that he was driving the tractor. Joe's father saw him playing on the tractor and called for him. Joe heard his father calling for him and got off the tractor really fast. When he did that, he fell off and hurt his arm. Joe was in pain and his father came running to check on him and picked him up and sat him on a bench and asked him why he did that. Joe looked at his father and said, "I wanted to be like you." Joe's father gave him a hug and asked him if he wanted to ride with him on the tractor. Joe did and after he got a bandage on his arm, he and his father rode in the field on the tractor.

Question: "Who was worried that Joe would climb on the tractor and hurt himself?"

Response: "Joe's father"

A:
yes