Grand Canyon

[Jim Colyer]

The Grand Canyon is in northern Arizona. It was carved by the Colorado River as the land rose. A cake and knife analogy is used. The river is a knife held stationary as the cake is uplifted. The Canyon took 7 million years to carve.

 

The Grand Canyon is 277 miles long and a mile deep, averaging 10 miles across. It is shaped like a bra or a woman's bosom. Two billion years of Earth's history are exposed. The Canyon continues to widen as the rims disintegrate.

 

Erosion by water, ice, wind and the course of the Colorado widen the Canyon. Water has the most impact. It gets into cracks between rocks and freezes. The cracks widen, and Canyon walls collapse.

 

Geologists study rocks. Paleontologists study fossils. Their work overlaps because fossils are found in rocks, an indication that they are the same age.

 

Rocks can be dated. Even if they could not, it is obvious from the fossil record as we dig deeper into the earth that life was simpler in the past. Only a dogmatist could deny evolution.

 

Sedimentary rocks were laid down by water. Less complex fossils are found in the different layers as we descend.

 

Layers of sedimentary rock form when oceans move in and out. Limestone forms when oceans move in. Shale forms when they move out.

 

Rocks in the Grand Canyon are from the Paleozoic Era. There are no rocks from the Mesozoic or Cenozoic. They either eroded away or were never laid down. That means there are no fossils of birds, reptiles or mammals. No dinosaurs. The Paleozoic is the era of shelled invertebrates. Trilobites flourished in Cambrian seas.

 

Kaibab Limstone is the top layer at the Canyon. It is 250 million years old. It formed at the bottom of an ocean and contains fossils of marine animals.

 

Coconino Sandstone is the remnant of sand dunes from 270 million years ago. It contains no fossils. Sandstone is solidified sand.

 

Hermit shale was deposited 280 million years ago. It contains plant fossils, indicating that it was above water. Shale is solidified mud.

 

Vishnu Schist at the bottom is 2 billion years old. Schist is metamorphic rock.

 

Geologic time:

CENOZOIC ERA - Mammals - Present-60 million years ago

MESOZOIC ERA - Reptiles - 60 million-220 million

Birds

Amphibians

Fish

PALEOZOIC ERA - Inverebrates - 220 million-540 million

 

PALEOZOIC ERA

Permian - 220 million years ago

Pennylvanian - Carboniferous 325 million

Mississippian - Carboniferous 360 million

Devonian - 410 million

Silurian - 440 million

Ordovician - 500 million

Cambrian - 540 million

Precambian Era - Bottom of the Grand Canyon. The oldest fossils are 3 billion year old microbes. The oldest rocks are 3.8 billion. The age of the earth is 4.6 billion.

 

The Grand Canyon offers the most complete geologic column on the planet. Rock layers are the same on both the north and south rims.

[Turtle]

The Grand Canyon is in northern Arizona.

as part of course study, i field-tripped there & hiked to the bottom & back with a geologist & group of students. one other older student was there to prove creationism; very amusing to listen to him press his angle with coy questions to the geologist. when you walk down, the mules have right of way and you have to get off the trail while they pass pissing & crapping on the trail. 110 deg F at the bottom in June. made jokes at camp about eating shish-kaibab for dinner. :hyper:

[Jim Colyer]

Great experience! I have read that it is easy to walk down the Canyon, but a real test walking back up.

[Turtle]

Great experience! I have read that it is easy to walk down the Canyon, but a real test walking back up.

 

that was my experience, yes. in fact, it is recommended to hike out a different trail than in. i forget the trail names, but there is no water on the down trail. we stayed as a group and took our lectures on the way down. at the bottom was water and a small stone building; a lot of people boat float to this point & then hike out.

 

there was one other water tap about half way out the up trail; not much worry about a bathroom as the sweating takes care of water excretion. :( it took me and my partner 12 hours to make the circuit :) ;i think only one other pair was behind us. :lol: great experience. :)