"excepting only yosemite, hetch hetchy is the most attractive and wonderful valley within the bounds of the great yosemite national park and the best of all the camp grounds. people are now flocking to it in ever-increasing numbers for health and recreation of body and mind. though the walls are less sublime in height than those of yosemite, its groves, gardens, and broad, spacious meadows are more beautiful and picturesque. . last year in october i visited the valley with mr. william keith, the artist. he wandered about from view to view, enchanted, made thirty-eight sketches, and enthusiastically declared the in varied picturesque beauty hetch hetchy greatly surpassed yosemite. it is one of god's best gifts, and ought to be faithfully guarded."
john muir, century magazine, 1909

john muir's thought above expresses what major change in americans' views of the natural environment?

answer; inductive techniques;

two jet streams that directly affect the formation of weather in the continental part are a polar jet and a subtropical jet. they are responsible for the transportation of weather systems, which directly affect people. the polar front is the boundary between cold air from the north pole and warmer equatorial air. both the polar jet and the subtropical jet blow from the west to the east, and follow the boundary between cold and warm air.

the strongest jet streams are polar jets, while subtropical jets are somewhat weaker.

the right answer is c. the polar jet stream is generaly stronger than the subtropical jet stream.

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)