Rivers, geology and culture (#1) - Arges, Romania

A river represents the perfect fusion between geology and culture.  Rivers  are characterizesd, generally speaking, both by erosion and deposition; this is where the geology aspect comes from.  Think of the Grand Canyon and you can visualize the results of river erosion through time.  Take a canoe down or up a river, stop on the river bank for lunch and look around; the canoe trip and the lunch break will help you witness river processes, deposition and their resulting features.
Rivers are also amazing "cultural centers", in the sense that human settlements usually started along a river.  Any major city in Europe for example is  associated with a river: Paris-Seine, Vienna-Danube, Frankfurt-Main, Bucharest-Dambovita, Rome-Tiber, and the list could go on...  This is where the cultural aspect comes from.
With this post, I am starting a geological-cultural trip along a river, the Arges River in Romania, to be more precise; I imagine I am a rock particle (or a water molecule) originating from the Southern Carpathians and traveling along the Arges River all the way to the Danube.  The trip will witness some amazing history (geological and human), culture and landscapes.
The Arges River headwaters are located in the Southern Carpathians, between the two highest mountain peaks in Romania: Moldoveanu and Negoiu.

Google map showing the headwaters of the Arges River, located between Negoiu and Modoveanu, the highest mountain peaks in Romania.  Top of the map is towards South.

Geologic sketch of the area around
the Arges River (modified after  Mutihac, 1990). Note that only
the geology relevant to the Arges River is represented in color.
Cn2= Serbota crystalline series; Cn1=Fagaras crystalline series;
Pg=Paleogene; m=Miocene; N=Neogene

The Arges River has its headwaters in the metamorphic rocks of the Fagaras Mountains.  The views are breathtaking, the weather is harsh and as a result, the few motels and chalets that exist in the area function only during the summer.
The upstream part of the Arges River is probably most famous because it parallels the second highest paved road in Romania - the Transfagarasan. The road was built in early 1970's in response to the Soviet invasion of Czechoslovakia. Ceausescu, the Communist President of Romania at the time, wanted to have quick access across the mountains in case the Soviets attempted a similar move in Romania.  The road was built with heavy human (forty people lost their life) and financial sacrifice.
The next posts will take us to the Vidraru lake, then through the most upstream permanent settlements (villages) along the river; this will allow us to explore more geology and culture.

Comparative geology - the tale of two rivers

I recently went on a canoe trip along the Trinity River (our track is shown by the red snaky line in the picture below).  We spent the day looking at sedimentary features associated with modern river systems, and by doing so, thinking about processes at work in rivers, and the resulting rock architecture.  As geologists, we often study modern environments (like rivers, beaches, deltas etc) to gather clues that help us understand the rocks and the processes that formed them.

The trip to the Trinity (more details in this post) reminded me of the Arges River in Romania; if looked from above, both have a lot in common.

Note that the scale of the two satellite images are similar, so the size of the geomorphic features can be easily compared.  The width of the meander belt in the two images is similar.  Two abandoned meander loops (red arrows) have similar dimensions and shape.  Their paleo meander belts (active sometime in the recent past and still visible on the satellite image) have similar widths (black arrows).

The zoomed satellite photos show that the size of the active channels are similar.  The Arges shows better the point bars within the active channel, but this is only because the picture of the Trinity was taken at near bank-full stage, where most of the point-bars are submerged.
These two rivers, although in somewhat different settings, would most likely create a very similar rock succession.  I have to take a canoe trip along Arges sometime in the future, and at that point I will have on the ground pictures from the both locations.  Until then, wait for the next post on the Trinity, and enjoy the birds-eye view of the two rivers.