INANIMATE NATURE: U-SHAPED POSTGLACIAL VALLEYS, V-SHAPED RIVER VALLEYS, MORAINES, PONORS, RIDGES, FOEN WINDS, AVALANCHES

U-shaped postglacial valleys

A valley is an elongated low area running in a certain direction. If it was created or transformed by a glacier then it is called a postglacial valley, also known as glacial troughs. The Tatra mountains were covered with ice during the ice age during the Pleistocene, which began 2,5 million years ago and ended about 10 thousand years ago when the last glaciers in the Tatra mountains disappeared (although, according to some scientists the Pleistocene hasn’t ended yet at all). The cross section of postglacial valleys is shaped like the letter U, which why they are often called u-shaped valleys. This particular shape was formed by massive glaciers moving slowly down the valleys while deepening them. Of course, the valleys were deepened the most where the ice was the thickest, which was in the middle. At the top of the valleys there were firns, which are patches of granular snow usually accumulated on high mountains and subsequently compacted into glacial ice. The firns were surrounded by rock walls which dropped boulders into the ice. Then, as the ice was moving so were the boulders, which were grinding the ground. In places where the surface was harder there were smooth, round boulders left, which are called Roches moutonnees or simply sheepbacks because they resemble backs of the sheep. In places where the ground was less hard there were holes created, which are known as the cirques. After the glaciers melted some of those holes were filled with water, thus creating beautiful postglacial lakes, which are known as ponds on Podhale.

V-shaped river valleys

The cross section of the valley that was formed through deep-seated erosion caused by the flow of water is shaped like the letter V, which is why they are called v-shaped valleys. In the Tatra mountains such valleys can be found in all the places that were not reached by the moving glaciers. They are mostly montane valleys, like Dolina Złotego Potoku or Dolina Przyporniaka. The slopes of the v-shaped vallyes can be gentle or steep, depending on the type of ground and how resistant to erosion it was. In some places, where the ground was more resistant there were cascades and waterfalls formed.

Moraines

The rock material which fell from the rock walls on the firns was carried along by glaciers and ice sheets down the valley. The debris not only carved the ground but it also formed so called moraines in places that were warm enough to melt down parts of the glaciers. As the glaciers melted the debris was left on its sides, where it formed lateral (side) moraines. In places where two valleys met they would merge and their lateral moraines would form a medial moraine.

Once the glaciers were low enough they melted and the debris accumulating formed terminal moraines, which are banks going crosswise across the valleys. If the glacier melted over a large area it would form ground moraines. Ground moraines can cover large areas. They show the levels of ice in the valleys during various periods of time. Sometimes a new moraine was formed on top of an old one.

In many cases there were lakes formed around the moraines. Some of those lakes are still there today, others disappeared as they were overgrown with plants. Wielka Młaka Pańszczycka is an example of such place – there used to be a lake there, but now it is a living raised bog.

Ponors

What exactly is a ponor? Ponors are places where rivers and creeks disappear underground. Basically, they are the opposites of the sources of rivers. Such phenomena occur in areas where the ground contains rocks which slowly dissolve in contact with water and carbon dioxide, like, for example, the limestone. They are called the karst phenomena.

The ponors can be found in many places in the Tatra mountains, such like Hala Gąsienicowa, where the ponors are located nearby the lower station of the cable railway going to Kasprowy Wierch. The water from Litworowy Staw Gąsienicowy disappears underground to show up again in Wywierzysko Goryczkowe in Dolina Bystra. There is also the ponor of Mokra Jama, which is located nearby the trail to Kasprowy Wierch, above the Murowaniec hostel.

The ponors are also to be found in Dolina Pańszczycy, nearby Czerwony Stawek Pańszczycki, where the rocks beneath the water change from granite into limestone. The water flows underground and after about 4 kilometres it springs in Wierzysko Olczyńskie, in a different valley – in Dolina Olczyńska.

The limestone that creates the ponors is often not visible, as it is covered with the moraines, however, there are noticeable depressions. They are the sinkholes, where the water goes underground.

Ridges (pl granie)

The ridges are steep mountain tops that were formed through the glacier activity. Before the ice age there were gentles slopes in the region of today’s Tatra mountains. The slopes were formed in mild climate conditions before the ice and snow came. After the climate cooling the glaciers began forming in the upper parts of the valleys which lead to severe erosion. As the rock and debris were falling and moving down the valleys, the moraines were forming and the rock walls were getting steeper and steeper. The mountaintops, previously gentle and round, were becoming steeper as well and if there was a glacier on the other side of the ridge too the erosion of the rock walls would eventually destroy the domed mountaintop leaving only the rock walls, thus forming a ridge. You can see the ridges up-close in the upper part of Dolina Pańszczycy, on the hiking trail of the Eagle’s Path (pl Orla perć).

Even though the glaciers melted down the steep rock walls still undergo the process of erosion. The rocks are weakened by the water repeatedly freezing and defreezing in their crevasses and by the constants changes of their temperature. As the rocks are falling off the debris is moving with avalanches and debris flows, which occur after intense ang prolonged rainfalls.

Foen winds (pl halny)

The wind known on Podhale as halny is a meteorological phenomenon which has great influence on both the environment and the people. Halny is a kind of foen wind (Foehn wind blows in the Alpine region and it was first described there), which is formed when masses of humid air from the south of the Carpathian Mountains, specifically from above Hungary, move to the north propelled by the high pressure coming from the area of Ukraine. As the air passes through the mountains it has to ‘climb’ the ridges and once it starts going down the valleys it loses some of its humidity, which falls on the south slopes in the form of the rainfalls. The air going down becomes warmer and drier.

The days when halny blows are typically cloudy and rainy on the south side of the Tatra mountains, while the ridges are cold and humid and the north side of the mountains is sunny, warm and dry, yet extremely windy. The clouds above Spisz and Liptowa appear as a wall (the phenomenon is known as the foen wall) and the clouds above Podhale take the shapes of lens and almonds, because of the co-called mountain wave in the atmosphere. The mountain waves are often used by the gliders, as they allow them to rise and glide very high.

Halny blows with high velocity and has great impact on the tree stands of the Tatra mountains. On the one hand, it breaks the trees and uproots them from the ground, while on the other hand it also spreads their seeds. Very often it also damages the roofs, fences and billboards on Podhale. When halny blows (and shortly before) there is a significant increase of the number of medical interventions related to heart diseases and blood pressure diseases, as well as of the number of police interventions related to quarrels, fights and suicides. At the same time the gifted people are much more creative than usually.

Avalanches

An avalanche, also known as a snowslide, is a rapid flow of snow down a slope caused by its own weight. There are also rock avalanches, however, they are usually called landslides. The snowslides occur much more often in the Tatra mountains and their frequency depends on weather conditions, the structure of the ice caps and the landform. There are also various types of the avalanches as tightly packed snow forms slab avalanches which are different from loose snow avalanches. Finally, there are also wet snow avalanches.

The avalanche danger is measured with the 5 point international scale in accordance to the likelihood and severity of the phenomenon. The first level of the scale means that the ice caps are solid and stable and the avalanche may only happen if there was substantial weight added to the steepest slopes. However, the analysis kept by the mountain rescuers show that at the first level of the scale the avalanches still sometimes cause tragic accidents. The following levels are: Moderate (2), Considerable (3), High (4) and Extreme (5).

In Poland there are no preventative measures employed to reduce the likelihood and size of avalanches, even though such measures are employed in other countries and on other mountain ranges. They include building snow fences and triggering the avalanches in a controlled way. The avalanches in Poland occur mostly in the protected parts of the national park and are treated as a natural process. The avalanches shape the upper border of the forests and increase the biodiversity by giving an access to light to lower plants.

The avalanches are a big threat for people who hike in winter which is why during the time of increased avalanche activity there are special reports issued daily, which describe the current level of avalanche danger. The places that are especially dangerous because of the likelihood of an avalanche are also marked with warning signs. It is recommended for the tourists to carry an avalanche kit with them at all times. The kit contains an avalanche beacon, a probe and a small shovel. The avalanche beacon is especially important, as if it is turned on, it allows to quickly locate a person buried under the snow. It significantly increases the chances of survival because after 45 minutes it becomes much less likely for the people to survive. Still, we must always remember that the kit is not a magical talisman and will not always save us. There is an old saying of the rescuers which goes: Even if you are an avalanche expert, remember that the avalanche does not know that.