The geological past of the Karkonosze Mountains

The Karkonosze Mountains are the highest part of the Sudeten Mountains. Contrary to popular belief, which is sometimes even expressed in school books, they are not old mountains. The were formed roughly in the same period as the Carpathians or the Alps. It was not a sudden, single event, but a process that has been going on for a few dozen million years. The differences among the abovementioned mountains are in the forming material, the way the mountains were shaped and also their appearance.
In general, the Alps or the Carpathians were formed from young, plastic deposits (mainly sand, silt, clay, organic matter) on the bottom of the ocean that once separated Europe and Asia from Africa. As the continents moved towards each other, the ocean almost entirely disappeared and the deposits were squeezed, folded and later uplifted, forming mountains.
The edges of the European continent north of the ocean responded to the squeezing pressure in the earth’s crust differently. They were made of much older igneous (granite) and metamorphic rocks (gneiss, mica, greenstones, etc.). They were harder and less plastic than sea deposits, so they were not folded but they cracked. Continent fragments separated by those straight cracks called faults were either uplifted or lowered with respect to each other. Mountains formed in this way are called horsts. The Sudeten Mountains and the higher uplifted Karkonosze Mountains are examples of horsts.
The dynamic landscape of the Tatras or the Alps, with deep valleys, sharp ridges and peaks, makes them look younger, while the rolling and vast Karkonosze Mountains, with domed summits and monotonous slopes make them look older. The difference in the looks lies in a considerable disparity in the altitudes. During the Ice Age, the Alps or the Tatras were occupied by numerous glaciers, which carved cirques and deepened the valleys. In this way they made the landscape look younger. In the much lower Karkonosze Mountains few glaciers made little impact on the landscape, so the original appearance of the mountains was largely preserved.
To put it shortly, the Tatras and the Karkonosze Mountains are both like mature women. The first woman is wearing a strong, post-glacier makeup, while the other one’s makeup is very moderate. We, like men often are, are misled by a false appearance, thinking that the Karkonosze Mountains are older.