Look at the stone on his smooth round surface sometimes visible grooves that resemble scars. Who inflicted these scars on the stone face?
In 1871, Russian scientist famous revolutionary PA Kropotkin, watching the spread of these stones, called them Erraticheskie (from the Latin word "erratikus" - wandering). The scientist suggested that much of northern Europe was covered with ancient continental glaciation. Moving ice moved from a huge number of different sediments, including glacial erratic. A winding hrapitsa distribution of precipitation in the form of the shaft indicates limit the spread of the glacier. Retreating glacier left traces in the form konechnomorennoy ridge. Generally all portable glaciers detrital material geologists called moraine.
A little away from our meadow on a high mound is almost a country road at right angles to konechnomorennoy ridge. But why for rarely used dirt road taken care to create a high mound? This is also the work of the glacier - Esker, formed by melting it. They mark the edge of the glacier Fire arising from his river flows. So, we have a typical glacial relief.
Currently, glaciers covered only 11% of the land. But in Earth's history occurred repeatedly era when the area occupied by ice, was much higher. The presence of ancient zledenin geologists to establish presence in sediments typical glacial deposits - moraines and sometimes the remains of ancient glacial relief. One of the oldest zledenin that there were 1 billion years ago, found in North America in the Great Lakes. Traces of glaciation, which we are now seeing our lawn was by ecological concepts recently - in the Quaternary period which began about 1-1.5 million years ago and continues today. During this time, large areas of Europe not once covered by glaciers. Center glaciers were Scandinavian Mountains. When the maximum glaciation some tongues of glaciers reached the middle reaches of the Dnieper and Don.
So, then, the role of the mythical Polyfema performed glacier. Glacier here he brought a huge boulder okatannuyu, polished, scratched him during a long trip. But where it took the glacier where our homeland valupa? You can try to answer this question pas. Since a piece of boulder stone and examine it carefully. Pebbles, sand, once erased glacier, are the most reliable sources of information about the history of the glacier, and modern glaciers suggest the possibility of future behavior.
It turns out fresh turn completely gray stone. Only the top op coated dark gray crust of prolonged exposure to it to sunlight, rain and wind. The color pink stone, sometimes almost red. In turn noticeable granular crystals of different minerals, sometimes light, sometimes dark, almost black. So it's granite-rapakivi granite! The word granite comes from the Latin "hrapum" - corn, and "rape" in Finnish - rotten stone. Indeed granite rapakivi granite on the surface easily destroyed. Not far from Odessa - on the banks of the Dnieper and the Black Sea - you can see numerous outcrops indigenous rape. Perhaps here, from Scandinavia for many hundreds of kilometers arrived on our lawn glacial erratic.
To get acquainted with granite, it is best to consider it under a microscope. To do this, go to the petrographic ( "PETROS" - stone, "Count" - I write) laboratory. But first glance the nearest ravine and take there are a few rock samples. On the wall of the ravine three distinct layers of different breeds. In the top layer of white, we easily found limestone. If it drip hydrochloric acid, it hisses and vsponytsya. Below lie the clay, but they are very dense and dark. Under the clay settles sandstone.
Typically geologists to study rocks prepare thin sections. Grinding - a thin (0.03 mm) plate rocks, sandwiched between the two to save stack-interest. It put under the microscope and see in passing and reflected light. I did not mention, gr can study in transmitted light. Most rocks and a small plate miperalov rays pass almost like glass. And that is not melted glass rock - quartz sand? In thin sections in transmitted light again turned our granite and zablyskav whole range of colors. Much of the field of view covers pale pink feldspar crystal.
Feldspars are the most common in the upper part of the lithosphere group aluminosilicate minerals sodium, calcium, potassium, barium. Their color is quite diverse: white, cream, pink, red, green, and others. Some feldspar used as jewelry and precious stones.