The idea that Earth is a magnet is far from new. It was first proposed in 1600 by a British physician named William Gilbert. Knowing it acts like a magnet is one thing. Knowing why it acts like a magnet is more difficult. In fact, finding out why is a fairly recent discovery. To find out why required new technology. It was the seismograph that made it possible to learn why the Earth acted like a magnet. Seismograph are used to study earthquakes. By studying earthquake waves they were able to learn about Earths interior. They discovered that Earth has an inner and outer core. The outer core consists of liquid metals, mainly iron and nickel. Scientists think that Earths magnetic field is generated here. It is caused by the motion of this liquid metal. The liquid metal moves as Earth spins on its axis.

What do scientists think to be the immediate cause of how Earth's magnetic field is generated? Choose the relevant options

Billy had a pet turtle that he took good care of, everyday. His turtle's name was Tumble. Tumble liked to walk around outside in the garden and dig small holes to sleep in. Billy loved Tumble and would visit him outside when he got home from school. Tumble's favorite food was oatmeal. So, every day after school, Billy would make Tumble a big bowl of oatmeal and take it outside for Tumble to enjoy. Tumble would see Billy and walk up to him as fast as a turtle can go. Billy would put the bowl down and wait for Tumble to come up to the bowl to eat from it. When Tumble reached the bowl, he put his nose on it. But, the oatmeal was too hot to eat. Billy reached down and blew on the hot oatmeal, to cool it down for Tumble to eat. Once the oatmeal was cool enough, Tumble could dig in and eat his big bowl of oatmeal. Billy loved to watch as Tumble ate his bowl of oatmeal, because Billy took good care of Tumble, everyday.

What were some of Tumble's favorite things?

Over the centuries, the living here has always been easy enough to attract a steady stream of immigrants. Bountiful food sources might have made Malaysia an inviting place for the contemporaries of Java Manin 230,000 b.c. But thus far, the country's earliest traces of homo sapiens, found in the Niah Caves of northern Sarawak, are fragments of a skull dating to 40,000 b.c. On the peninsula, the oldest human-related relics (10,000 b.c. ) are Stone Age tools of the Negritos. These small, dark Melanesians are related in type to Australian aborigines and are confined today to the forests of the northern highlands. By 2,000 b.c. , these timid, gentle nomads hunting with bow and arrow were driven back from the coasts by waves of sturdy immigrants arriving in outrigger canoes equipped with sails. Mongolians from South China and Polynesian and Malay peoples from the Philippines and the Indonesian islands settled along the rivers of the peninsula and northern Borneo. They practiced a slash-and-burn agriculture of yams and millet, a technique that exhausted the soil and imposed a semi-nomadic existence from one jungle clearing to another. Families lived in wooden longhouses like those still to be seen today among the Iban peoples of Sarawak. Another unit was added on to the communal dwelling each time a marriage created a new family. Other tough migrants from the South Seas settled along the coastssailors, fishermen, traders (for the most part pirates)known euphemistically as orang laut (sea people).
Who were the timid,gentle nomads who were driven back from the coasts?