Golden river meanders
River meanders lit up by fall foliage. Grand Staircase-Escalante National Monument.
Interestingly enough, this was taken from a viewpoint at a turnout on a high ridge between two canyons (see map). The high ridge has a layer of conglomerate (right there at the parking area - if you look close you can see some of the rounded rocks in the near foreground) itself deposited in an ancient streambed that armored the terrain and protected it from erosion. So the former streambed became a ridge as everything else eroded around it in a classic case of inverted releif. The meandering channel seen in the canyon suggests that the channel started out freely meandering and slowly cut down into the surrounding terrain (Navajo sandstone).
So here is the geological story:
1) Dunes everywhere in one of the largest sand seas that ever existed on Earth. Early Jurassic 174 - 190 million years ago.
2) The dunes and sands turn to stone.
3) More layers get built up, some erosion on the top of the layer stack (way above the sandstone).
4) A stream channel comes down a valley carved in the upper layers of the ancient layer stack.
5) Conglomerate river rocks and gravels are deposited in the channel.
6) Erosion occurs. The conglomerate protects the rock below it from being eroded.
7) Channels meander freely around gently sloping terrain.
8) The channels begin to cut in deeper, locks in ancient meander pattern as it starts to carve into the Navajo sandstone.
9) The surrounding sandstone erodes into a slickrock terrain. The conglomerate-covered ridge still standing proud above eroded terrain.
And the result is the beautiful landscape in this part of Grand Staircase-Escalante National Monument.
Golden river meanders
River meanders lit up by fall foliage. Grand Staircase-Escalante National Monument.
Interestingly enough, this was taken from a viewpoint at a turnout on a high ridge between two canyons (see map). The high ridge has a layer of conglomerate (right there at the parking area - if you look close you can see some of the rounded rocks in the near foreground) itself deposited in an ancient streambed that armored the terrain and protected it from erosion. So the former streambed became a ridge as everything else eroded around it in a classic case of inverted releif. The meandering channel seen in the canyon suggests that the channel started out freely meandering and slowly cut down into the surrounding terrain (Navajo sandstone).
So here is the geological story:
1) Dunes everywhere in one of the largest sand seas that ever existed on Earth. Early Jurassic 174 - 190 million years ago.
2) The dunes and sands turn to stone.
3) More layers get built up, some erosion on the top of the layer stack (way above the sandstone).
4) A stream channel comes down a valley carved in the upper layers of the ancient layer stack.
5) Conglomerate river rocks and gravels are deposited in the channel.
6) Erosion occurs. The conglomerate protects the rock below it from being eroded.
7) Channels meander freely around gently sloping terrain.
8) The channels begin to cut in deeper, locks in ancient meander pattern as it starts to carve into the Navajo sandstone.
9) The surrounding sandstone erodes into a slickrock terrain. The conglomerate-covered ridge still standing proud above eroded terrain.
And the result is the beautiful landscape in this part of Grand Staircase-Escalante National Monument.