Introduction to Earth Science Chapter 1 Earth Science, 12e Introduction to Earth Science Chapter 1

Earth Science Encompasses all sciences that seek to understand Earth’s neighbors in space Earth Science includes Geology – literally the “study of Earth” Oceanography – a study of the ocean

Earth Science Earth Science includes Meteorology – the study of the atmosphere and the processes that produce weather Astronomy – the study of the universe

People and the environment Surrounds and influences organisms Physical environment encompasses water, air, soil, and rock Term “environmental” is usually reserved for those aspects that focus on the relationships between people and the natural environment

People and the environment Resources An important focus of the Earth sciences Includes water, soil, minerals, and energy Two broad categories Renewable – can be replenished (examples include plants and energy from water and wind) Nonrenewable – metals (examples include metals and fuels)

People and the environment Population Population of the planet is growing rapidly Rate of mineral and energy usage has climbed more rapidly than the overall growth of population Environmental problems Local, regional, and global

People and the environment Environmental problems Human-induced and accentuated Urban air pollution Acid rain Ozone depletion Global warming Natural hazards Earthquakes Landslides

People and the environment Environmental problems Natural hazards continued Floods Hurricanes World population pressures

Scientific inquiry Science assumes the natural world is Consistent Predictable Goal of science To discover patterns in nature To use the knowledge to predict

Scientific inquiry An idea can become a Scientific method Hypothesis (tentative or untested explanation) Theory (tested and confirmed hypothesis) Paradigm (a theory that explains a large number of interrelated aspects of the natural world) Scientific method Gather facts through observation Formulate hypotheses and theories

Scientific inquiry Scientific knowledge is gained through Following systematic steps Collecting facts Developing a hypothesis Conduct experiments Reexamine the hypothesis and accept, modify, or reject Theories that withstand examination Totally unexpected occurrences

Early evolution of Earth Origin of Earth Most researchers believe that Earth and the other planets formed at essentially the same time Nebular hypothesis Solar system evolved from an enormous rotating cloud called the solar nebula Nebula was composed mostly of hydrogen and helium

Early evolution of Earth Origin of Earth Nebular hypothesis (cont’d) About 5 billion years ago the nebula began to contract Assumes a flat, disk shape with the protosun (pre-Sun) at the center Inner planets begin to form from metallic and rocky clumps Larger outer planets began forming from fragments with a high percentage of ices

The Nebular hypothesis Figure 1.8

Early evolution of Earth Formation of Earth’s layered structure As Earth formed, the decay of radioactive elements and heat from high-velocity impacts caused the temperature to increase Iron and nickel began to melt and sink toward the center Lighter rocky components floated outward, toward the surface Gaseous material escaped from Earth’s interior to produce the primitive atmosphere

Earth’s “Spheres” Hydrosphere Ocean – the most prominent feature of the hydrosphere Nearly 71% of Earth’s surface About 97% of Earth’s water Also includes fresh water found in streams, lakes, and glaciers, as well as that found underground

Earth’s “Spheres” Atmosphere Biosphere Thin, tenuous blanket of air One-half lies below 5.6 kilometers (3.5 miles) Biosphere Includes all life Concentrated near the surface in a zone that extends from the ocean floor upward for several kilometers into the atmosphere

Earth’s “Spheres” Solid Earth Based on compositional differences, it consists of the crust, mantle, and core Divisions of the outer portion are based on how materials behave Lithosphere - rigid outer layer Divisions of Earth’s surface – continents and ocean basins

Earth’s layered structure Figure 1.13

Earth system science Earth is a dynamic body with many separate but highly interacting parts or spheres Earth system science studies Earth as a system composed of numerous parts, or subsystems System – any size group of interacting parts that form a complex whole

Earth system science System Closed systems are self-contained (e.g., an automobile cooling system) Open systems – both energy and matter flow into and out of the system (e.g., a river system)

Earth system science Feedback mechanisms Earth as a system Negative-feedback mechanisms resist change and stabilize the system Positive-feedback mechanisms enhance the system Earth as a system Consists of a nearly endless array of subsystems (e.g., hydrologic cycle, rock cycle)

Earth system cycles Figure 1.21

Earth system science Earth as a system Sources of energy Sun – drives external processes such as weather, ocean circulation, and erosional processes Earth’s interior – drives internal processes including volcanoes, earthquakes, and mountain building Humans are part of the Earth system