Big Idea IV: Physical and chemical principles are unchanging and drive both gradual and rapid changes in the Earth system

Earth processes operating today, everything from local erosion to plate tectonics, are the same as those operating since they arose in Earth history, and these processes are obedient to the laws of chemistry and physics. While the processes that constantly change the planet are essentially fixed, their rates are not. Tipping points are reached that can result in rapid changes cascading through Earth systems. For example: 

• Extending from southern Maine up through New Hampshire, the White Mountain series initially formed deep within the curst as plumes of magma rose from the mantle. As the plate moved over a hot spot, magma pushed upward through the crust to form the string of igneous bodies. It is thought that the Hawaiian Islands may have formed (and are still forming!) in a similar manner.
• Today, the ice sheets of Greenland and Antarctica make up some 95% of all the current glacial ice on Earth. The study of these modern glaciers and their influences on the environment, such as the formation of U-shaped valleys, is key to interpreting glacial deposits of the past, which are thought to have formed under the same processes as those operating today.