Yosemite

B. Yosemite has a geologic history that can be discerned in

II. The beauty of Yosemite today has a history.

Scientists can see history in the rocks, the formations,

and the geologic activity of the area.

B. We can see these formations from Valley View.

III. The age of the rocks is important in determining their formation.

A. The oldest rocks are 450 million years old.

1. Yosemite had a different landscape.

2. Yosemite was affected by the atmosphere and radiation.

3. Yosemite was part of North America, and North America

was part of the supercontinent of Pangaea.

During the Silurian period, oxygen increased in the

C. Rocks of Yosemite were thrust above the surface of the sea

350 million years ago for the first time.

2. These were transformed by intense pressures and high

3. These form the encirclement of Yosemite today.

IV. Yosemite and the Sierra was eroded to a low, gentle landscape.

A. This was during the Permian period.

B. This was when a second period of mountain-building began.

There is evidence for these successive periods of uplift.

2. There is evidence for the breakup of the Pangaea which

. . .
d above the sea for the first time some 350 million years ago, just before the Devonian period gave way to the Carboniferous period. It was at that time that the western edge of the supercontinent Pangaea underwentan orogeny, or a mountain building episode. This took place over tens of millions of years as the major sediments of the area were slowly thrust eastward by large, global forces that resulted in a low-northeast-trending range of fold mountains not unlike the Appalachians of today. The landscape was changed, as were the rocks that form it. Marine sediments such as shale and other rocks were exposed to intense pressures and high temperatures, and they were transformed into slate and other metamorphic rocks. The remnants of the rocks of that time, together with more abundant and younger metamorphic rocks, encircle Yosemite Park's granitic landscape. There are two significant gaps in this encirclement. The segment that runs from Mather Ranger Station north-northeast to Wheeler Peak and the smaller segment from Mariposa Grove northwest to Wawona are those gaps. And the metamorphic rocks tend north-west, not northeast, so that two arms extend northwest well into the Park: the Ritter Range metamorphics extend continuously nor
. . .

Some common words found in the essay are:
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Approximate Word count = 2474
Approximate Pages = 10 (250 words per page)

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