Big Idea 1: The Earth is a system of systems

The Earth is composed of many systems, which cycle and interact in both space and time. It is also part of a multitude of systems, nested in larger systems such as the solar system and the universe. Systems are composed of an untold number of interacting parts that follow simple rules; they can and do evolve. For example:

Outlining the geologic history of any region demonstrates the concept of the Earth as a system of systems. Plate tectonics drives the formation of mountains. Subsequent weathering and erosion of the uplifted mountains leads to the formation of deltas in adjacent shallow seas. And with uplifted continents, shorelines change and the distribution of marine communities are altered.

The planet’s systems are intimately connected: the forces of one system affect other systems nested within it. As plates collide, systems that drive plate tectonics are obviously linked to the formation of mountains, but they are ultimately linked to and influence much smaller systems. The intense heat and pressure resulting from collisions can lead to the metamorphism of existing strata, or it can melt existing rocks to later form igneous rocks.

See Chapter 6: Glaciers to learn more about glacial lakes, including Lake Missoula and Lake Agassiz.

Each of the remaining ideas operates across multiple systems within the larger Earth system.

As glaciers extended from the north during the ice age, they cut into river valleys. This glacial system shaped the landscape of upper North America, deepening and widening existing rivers and damming huge lakes that later emptied in great torrents. For example, Glacial Lake Missoula emptied in a catastrophic flood that carved out the Channeled Scablands in northern Idaho and eastern Washington while also leaving behind huge sediment deposits. Had glaciers never advanced this far south, the erosional forces that led to the formation and draining of these lakes would have never been set in motion. The interaction of climate, rock, and water has shaped every natural landscape on the planet. Humans and other living things build upon (or tear down) the foundations laid down by these systems, furthering their interplay.