The Earth is composed of different layers that include the crust, the mantle, the outer core and the inner core, each of these layers and the features of them have been discovered throughout the years by topographers, and other experts mainly by studying seismic waves. This can be explained as seismic waves that occur due to earthquakes, eruptions, explosions and other phenomena, travel through the different layers of Earth and depending on which layer they are they display different features and speed which is the main information scientists used to determine the layers of Earth and other features of Earth's interior. Thus, it is how seismic waves travel the one that provides scientific data about the earth's interior.
The NAFTA (North American Free Trade Agreement) is the agreement that has lowered trade barriers between Mexico and the rest of North America. It was signed January 1, 1994.
