Lecture 1. Physical geography encompasses the field of Earth systems science, the area of study that seeks to understand Earth as an interacting set of physical, chemical, and biologicalsystems. Nature doesn’t know about biology without geology – in the past, we as humans liked to “silo” or separate biology, geology, soil science, chemistry, and ecology into separate fields. Earth’s systems include the biosphere, atmosphere,hydrosphere, and lithosphere. Let’s orient ourselves to the unique properties and role of each sphere and how they are all connected.