The Hrádky Nature Reserve is situated between the villages of Osiky and Chlébské on the border of the South Moravian Region and Vysočina. It was declared in 1991 on an area of less than 25 hectares in Sýkořská highlands by the regional office of the South Moravian Region.
The main dominant feature of this area is the peak Sýkoř (702 m above sea level), from its main peak turns a number of minor ridges. One of them is the peak of the Hrádky Nature Reserve (628 m above sea level).
In addition to this nature reserve, the natural monument Kačiny and the natural monument Habrová are situated on the opposite slopes across the Chlebský creek valley. The most well-known locality in this part is the nature reserve of the Chlebský creek Valley, where the original vegetation communities with the dominant spring pudding were preserved in the deeply cut valley.
The reason for protection is the uniquely preserved natural maple beech community at the 4th and 5th vegetation level (vertical stratification of ecosystems). The locality is remarkable mainly from a geological and geomorphological point of view, as an example of stored rock ratios and selection by frost weathering. The territory is also significant ornithologicaly. The area of the reservation includes a summit area and a part of the slopes of the same name hill, with an altitude of 627 meters, belonging to the Hornosvratecká Highlands.
It is a bizarre rock group, which was created by frost weathering in the Sýkořská highland above the valley of Chlébský creek. Around the rocks, there is an old beech growth, where ash, elm and maple are associated with the dominant beech and maple.
At the very top, there are several distinctive mushroom-like rockies, created by frost weathering. For a larger group of these shapes, the term "rock town" has been widely used today. An interesting phenomenon is the horizontally deposited rock layers, sinking in regular blocks on top of each other, including sinking mineral veins.
Frost weathering is a type of physical weathering. It is a process in which the rock breaks down without any significant changes in their chemical composition. Its cause is changes in the intensity of insolation, which leads to both thermal and volumetric changes in the surface layer of the rocks. All rocks are composed of different mineral combinations, all rocks have a certain temperature-pressure limit in which they cease to be stable and in which their integrity is impaired due to cracking, etc. Due to tectonic activity and consequent rocks extinction, they exhibit different temperature and pressure conditions. The gradual drop in temperature and pressure leads to the cooling of the rocks, resulting in shrinkage and cracking or melting. Liquid water penetrating the resulting cracks is then transformed into ice, resulting in increasing pressure in the cracks and tearing off a part of the rock mass (the ice tends to increase its volume in the transition to the solid phase, the change can reach up to 1/10 volume). Regular repetition of thawing and freezing of the water in the crack will result in its increase. Expertly, this process is called frost weathering and is typical of the exposed mountain peaks.
If you are interested in this site, you can take a look at an interesting video from Tišnov Television (see the link below and / or it will definitely be better, take a look at this interesting locality with your own eyes
You are in a public place that is also a nature reserve, so there are some restrictions. Use paths to access, do not go outside.
Video - příroda Tišnovska
Attention - you are in the nature reserve and so the entrance is only possible on the path! Do not drive cars out of paved roads, do not ride bicycle on unpaved paths, do not burn fires, and leave dogs on a leash. You are in nature - behave quietly and calmly. This locality is an occurrence and nesting place of a specially protected species of Great Raven - you are at his home. Do not destroy native rocky outcrops by climbing, throwing stones, etc. Nature has been here for thousands of years and there is no need to destroy its production.
Your tasks are:
1) At the initial coordinates, estimate the height of the largest rock blocks. Describe me in details, how do you imagine the creation of these rock blocks. Dont copy me the sentences from listing. Try it with your own words.
2) What is the type of rock, you think?
3) Find a mineral vein in the rock. What is the color, depth, and what kind of mineral it is?
4) Please attach some photos of you or your GPS in a nice geological place.
Your right answers send me via email through my profile, than you can log your visit. If your answers aren't correct, I will give you an echo. Please respect a rule - 1 log = 1 email with answers. In that case i will be uncompromising, who will log without sending answers, he will be deleted. It is a proof for me, that you were there and do something for a point.