Chihuahua Dog Breed. First discovered in Mexico, the Chihuahua is best known for being the smallest dog breed in the world. Extremely loyal to its owner, the breed has recently become a popular culture icon in the United States, most notably Paris Hilton's Chihuahua, Tinkerbell. Physical Characteristics.
Earth formed around 4.54 billion years ago by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean; but the atmosphere contained almost no oxygen and so would have been toxic to most modern life including humans.
Gradually, the dust and gas came together, forming the earth. In those early days over 4 billion years ago, the earth was mostly made up of liquid rock in volcanoes and was pounded by collisions from other things in space. Over time, the earth began to cool, and more solid layers formed, creating the earthâs crust. Sometimes people talk about the earthâs âspheresâ. The spheres of the earth are a way to describe some of the different, large-scale types of matter on the earth. There's the atmosphere, which contains