The Colorado river takes a Big Bend from Brownwood to Granite Shoals. Elsewhere it is fairly straight. I am curious why.
I know the Balcones uplift occurred around 10 million years ago. By studying the river basin from Austin to Brownwood you can detect an extreme bias of the river bed towards the eastern edge of the river basin along U.S. 183 of probably 20-50 miles. On the other side, the basin extends more than 100 miles to the west of the river bed with full fledged contributory rivers. The cause of this bias would seem to be the Balcones uplift, which suggests the Colorado River's Big Bend course was set prior to the Balcones Uplift. That is in 10 million years the river basin boundary has altered drastically with a general shift to the west while the river bed course has remained static.
A crude Google topographic survey shows that the area adjacent to the Big Bend of the Colorado is a flat plain occasionally intruded with well advanced erosional cuts from major streams. So how far back in time prior to the Balcones Uplift was the Colorado river course set? And was this Big Bend caused by the remnants of the Llano Uplift that I have seen on some geology maps as having formed islands during prior episodes of limestone deposition in Central Texas?
I know the Balcones uplift occurred around 10 million years ago. By studying the river basin from Austin to Brownwood you can detect an extreme bias of the river bed towards the eastern edge of the river basin along U.S. 183 of probably 20-50 miles. On the other side, the basin extends more than 100 miles to the west of the river bed with full fledged contributory rivers. The cause of this bias would seem to be the Balcones uplift, which suggests the Colorado River's Big Bend course was set prior to the Balcones Uplift. That is in 10 million years the river basin boundary has altered drastically with a general shift to the west while the river bed course has remained static.
A crude Google topographic survey shows that the area adjacent to the Big Bend of the Colorado is a flat plain occasionally intruded with well advanced erosional cuts from major streams. So how far back in time prior to the Balcones Uplift was the Colorado river course set? And was this Big Bend caused by the remnants of the Llano Uplift that I have seen on some geology maps as having formed islands during prior episodes of limestone deposition in Central Texas?
