Hi All. During the Paleozoic Era (575 to 270 million years ago) the region now occupied by the Sierra Nevada Mountains lay beneath the sea receiving sediments from the North American continent to the east. Tens of thousands of feet of sediments formed sedimentary rocks and extended the shoreline to the west. Toward the end of the Paleozoic Era the North American continental plate began to drift away from the super-continent of Pangea and moved westward. It began to override the Pacific Ocean Plate that was drifting eastward. The Pacific plate was forced to dive underneath the continental plate. The incredible pressure and friction melted portions of both the Pacific plate and the North American plate and granites distilled which rose to intrude the overlying sedimentary and metamorphic rocks. This plug of magma eventually cooled and solidified to form the granites exposed as the Sierras today. Pushing, grinding, heat and pressure continued to lift and fold the Sierra area until about 10 million years ago. The old sedimentary rocks and volcanic rocks were transformed by heat and pressure into a new form called metamorphic rocks.

Beginning about 130 million years ago, through erosion, the block of granite that was to become the Sierra became exposed to the elements and began to erode and still continues today. To account for the vast amount of eroded sediments found in the Central Valley, the pre-Sierra mountains must have been at least 15,000 feet high before finally being eroded into gently rolling uplands about 65 million years ago.

About 30 million years ago, an era of volcanism began in the Sierras that was of massive proportions by today’s standards. Here in the Northern Sierra around Lake Tahoe, the Sierra was covered by thick layers of volcanic ash and volcanic rock (andesite and rhyolite) expelled by the volcanoes.

In the middle of this era, about 10 million years ago, the Sierra began uplifting and are still rising this very moment. Staggered, parallel faults formed along the eastern edge of the range. The area to the west rose, and to the east, what is now the Carson Valley, dropped. Even though the eastern slopes of the Sierra rise sharply from the Carson Valley, the valley has filled with sediments obscuring the real consequences of this uplift. While the mountains rise about 9,000 to 11,000 feet above the valley, total uplift was about 19,000 feet!

One cannot describe the beauty of the Sierras and no picture can capture the feeling one gets when seeing the mountains for the first time, or for the hundredth time. One has to stand at the base of a rock cliff and look up to see the grander of the Sierras. I have to wonder at times how it is that something that had a violate birth can be so beautiful and yet so treacherous.

We returned by the way of Sonora Pass, which tops out at 9,624 feet. As we were driving down the other side I saw mountains that was nothing but rock. I had to stop to look at them. They were sheer rock that went almost straight up. Looking up at them I saw them as pillars of a cathedral and the sky was the roof. They made me feel insignificant and that there was nothing that man could do that would equal the beauty. I felt that we were intruders and that we did not belong there.

I know that one day in the future they may not be there as they will return to where they were born only to start over again. Will they be as they are now, or will they be something altogether different? I'm sure that which ever it will be there will be another Petra and Don looking at them and wondering the same. How can anything that was born catastrophically be so beautiful, or peaceful and yet so treacherous at the same time? Take Care…Don in creepy town