Picture yourself hiking in a narrow canyon in Utah. The canyon is dry and it hasn’t rained for weeks. You see some thunderhead clouds in the sky, but not one drop of rain all day. Nevertheless, a small rush of water starts to run through the canyon, turning it into a creek. There must have been a heavy rainfall somewhere nearby. Water runs down the sides of the canyon, forming little waterfalls. You realize that there could be a flash flood coming! You turn quickly up a side trail to higher ground before you are washed down the canyon.

Soon, you are safe above the canyon. It’s scary watching the wild, brown water rushing through the canyon bottom where you were just hiking. That was a stressful situation, but it lasted only a short time. What if this were an action movie? Next you might have to run away from a herd of stampeding cows and then put out a wildfire. The stress would go on and on.

Describe the effects that constant stress can have on your body functions.

sorry i cant read this sorry

nasa 3

the earth’s crust is broken into separate pieces called tectonic plates (fig. 7.14). recall that the crust is the solid, rocky, outer shell of the planet. it is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. both types of crust rest atop solid, upper mantle material. the upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar.

each tectonic plate is free-floating and can move independently. earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. the term fault is used to describe the boundary between tectonic plates. most of the earthquakes and volcanoes around the pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. other observable results of short-term plate movement include the gradual widening of the great rift lakes in eastern africa and the rising of the himalayan mountain range. the motion of plates can be described in four general patterns:

collision: when two continental plates are shoved together

subduction: when one plate plunges beneath another (fig. 7.15)

spreading: when two plates are pushed apart (fig. 7.15)

transform faulting: when two plates slide past each other (fig. 7.15)