Euphrates river

The Euphrates River originates in the mountains of Turkey, flows southward into Syria, and then turns east-southeast through eastern Syria and Iraq. Eastern Syria is a dry desert. Areas near the Euphrates have water available for irrigation, and the resulting vegetation shows up as dark areas. If water is not available, the land is dry sand and rock, and has a lighter color.

In the picture above, the Euphrates River is flowing from left to right through a mesa in eastern Syria. The low farmland both upstream and downstream from the mesa is about feet above sea level while the mesa ranges from feet to feet. Information on the origin of the mesa is lacking, and the Google Earth image has relatively low resolution. Thus, its geologic history is not known and the following eyeball analysis by the author should be considered speculative.

Five to ten million years ago the Euphrates River flowed through the valley. The mesa did not exist. Sometime during the last few million years, volcanic eruptions of fluid lava covered the area that is now the mesa. These volcanic eruptions would form temporary dams across the river. The river would quickly overflow interim layers that were built up, and try to start cutting a canyon down through the mesa. However, subsequent eruptions and lava flows would fill in these initial attempts to cut a canyon, and leave a new flat surface.

The volcanic eruptions ended perhaps one to two million years ago Since then the Euphrates has cut down through the mesa to generate its canyon. Ordinary erosion has also removed some of the surrounding terrain that was not protected by the hard lava layer. The steep sides of the canyon plus the fact that they have not eroded very far back from the river indicate that this has all been done very recently.