Geology and Earth Systems Overview

Study Notes

Geology is the study of Earth, its origin, materials, geomorphology, and its historical and present forms
Geology, from Greek words geo and logos, is the study of Earth
Oceans cover over 70% of Earth's surface
Earth is composed of atmosphere, hydrosphere, lithosphere, and biosphere

Earth's radius is about 6370 kilometers
Most of Earth consists of rocks
Rocks are composed of minerals
Geologists study the origins, properties, and compositions of rocks and minerals
Geologists explore Earth for resources, including water beneath the surface

Physical geology studies Earth materials and processes on the surface and within Earth
Historical geology studies Earth's origin, evolution of continents, oceans, atmosphere, and life

Geology combines with other scientific disciplines to form new fields, such as Engineering Geology (geology + engineering), Geochemistry (geology + chemistry), Geophysics (geology + physics), and Paleontology (geology + biology)

About 4.6 billion years ago, a rotating cloud of dust and gas (solar nebula) formed Earth
This cloud primarily consisted of hydrogen and helium
Small gravitational forces caused the cloud to condense into a sphere
The sphere then spread into a disk, with matter concentrated at the center to form the proto-Sun
Aggregates of particles stuck together, attracting more particles and developing stronger gravitational forces
This growth created small rocky spheres (planetesimals) ranging from a few kilometers to 100 km in diameter
Planetesimals merged into large planets, including Earth
Simultaneously, the protosun’s gravitational attraction pulled gases inward causing extreme pressure and temperature
This caused Hydrogen nuclei to combine to form helium and releasing large amounts of energy, marking the birth of the Sun. This is called nuclear fusion, and it continues to this day

The closest planets to the Sun (Mercury, Venus, Earth, and Mars) are rocky with metallic centers and are called terrestrial planets
The outer planets (Jupiter, Saturn, Uranus, and Neptune) are mostly liquid and gaseous with small rocky and metallic cores and are called Jovian planets

Earth is layered, with a dense, hot core composed mainly of iron and nickel
The thick mantle, mostly solid rock, surrounds the core, comprising 80% of Earth's volume
The crust is a thin surface layer also composed of rock
Earth's temperature and pressure increase as you move deeper
The mantle rock is hot enough (1.2%) to melt and flow slowly
The outer core is molten metal
The inner core is solid metal under extremely high pressure

The mantle mainly consists of solid ultramafic peridotite
Density increases from top to bottom
Convection currents (hot rising, cool sinking) occur in the mantle
Mantle depth is 2885 km and includes the upper mantle (0-660 km), lower mantle (660-2900 km), and transition zone (400-660 Km)

Continental crust is thicker (35-40 km) and less dense than Oceanic crust (7-10 km)
Continental crust is mainly granite, while oceanic crust is mainly basalt

Predicting Earth's system behavior and the universe
Conserving soils and maintaining agriculture
Maintaining water quality
Reducing suffering from natural hazards
Earth Resources (Energy: Oil, Natural Gas, Coal, Uranium, Geothermal; Metals: Fe, Cu, Al, Pd, Zn, Au, Ag; Nonmetals: Sand, Gravel, Limestone, Gems)
Natural Hazards (Tsunami, Volcanoes, Sandstorms, Hurricanes, Floods, Desertification, Earthquakes, Landslides, Subsidence)
Military applications