The Carnic Alps (Alpi Carniche in Italian, Karnische Alpen in German) are a large mountain range in the Southern Alps, wedged between the Sexten / Sesto Dolomites to the west and the Julian Alps to the east. In the north you find the Gailtal Alps whereas to the south the "Prealpi Carniche" finally drop down to the plain of the Po River. Geologically the Carnic Alps are among the most important and most complex mountain ranges of the Alps (world?), since they are located directly in the region, in which the massive build-up of the Alps occurred ages ago. This results in a complex layering of the different rock composites which gave way to a number of "Geo Trails" where you can inform yourself with the help of displays placed to the sides of the trails. For more geology details, see the section below.

Besides having been the frontline in the forming of the Alps the Carnic Alps Main Ridge in the north of the range was the theatre of battle during World War I. Austro-Ungarian troops fought the Italians here in fierce battles and across the whole ridge you can see multiple proofs of the fighting 90 years ago. You'll find the actual trenches, caves dug into the rock and collapsed (sometimes still standing) forts and positions everywhere. See the Peralba Trip Report if interested in this history. 

Though the war resulted in a complete upheaval in the political landscape of Europe (especially in the eastern part of the Austrian empire), the actual military gains were minimal. The peace treaties of Versailles and St. Germain did more than four years of fighting. It is interesting - and sad - that the ancient peoples, actually living in the fighting zones, Furlani, Ladini, Rhaetian - had to suffer most and got shifted around in the new landscape without having a word in the proceedings.

Carnic Alps geology

As already mentioned in the overview section, the geology of the Carnic Alps is very complex. This is certainly true for the main ridge which runs from west to east along the Gail- and Lesachtal Valleys (actually one large valley which has been named differently in different sections - in the following paragraphs I will refer only to Gailtal meaning both). The valleys are part of the peradriatic fault, the geological boundary between the North African plate and the European one. The fault runs from Lago Maggiore directly through Locarno to Veltlintal, later to Adamello, before it reaches Pustertal / Val Pusteria and Gailtal. In the east it crosses the Karawanke before heading south to the sea again.

In both Pustertal, the valley of the river Drau / Drava, and Gailtal the fault runs directly through the centre, the effect of which can nicely be seen by the difference of the rock composition north and east of the valley. While to the north the Zillertal Alps and Hohe Tauern are composed of solid eruptive rocks (granite, gneiss and the like) to the south most of the mountains are composed of limestone or the limestone-like Dolomite. In the area of the Carnic Alps however things get even more complicated.

What happened? First of all the area was covered by seas twice for long amounts of time. The first of these seas covered today's Carnic Alps in the Ordovicium Age. Sediments were formed and 440 million years ago a first "event" triggered the first build-up of mountains in the area. A porphyry plate was pushed over the sedimentary rocks. Remains of this plate can still be seen along the main ridge.

Erosion did away with most of the built-up mountains. Some 350 - 400 million years ago the second sea started to cover the area and overall it lasted 200 million years. This was the so-called Thetis Sea which also is responsible for the creation of the Dolomites. Huge coral atolls were formed the remainders of which are the mountain groups of the Dolomites. For instance look at the map of Langkofel / Sassolungo in the Dolomites (see below) and you will be able to see the atoll form still.

200 million years ago the final formation of the Alps began. And here the the Carnic Alps Area again was special. The mountains were kind of folded upwards, but this action took place in the form of waves which often overtook each other. With the waves "breaking" over the fault line the layering of the rocks became more and more complicated. Suddenly (think of it on a geological scale) old layers were sandwiched between younger ones, sometimes even layers of the same age several 100m apart with layers of all ages in between.

And this is what you still can find in the Carnic Alps today. The area around the highest summit, Hohe Warte (2780m) is the most complex, and thus most interesting. It is there that a so-called "Geo Trail" has been created, informing the hikers and climbers about the massive upheaval that took place 200 million years ago. These Geo Trails exist in more than one place so that - while visiting the area - you'll certainly run into one of them.

From www.summitpost.org