Top 10 geology factsGeology quiz
This kind of tilted forest is a common sight in subarctic taiga. What is this phenomenon caused by?
The soil. The permafrost prevents trees from developing a deep root system. Climate variations or forest fires can thaw the upper extents of the permafrost, creating a ground slump called thermokarst.
Which of European peninsulas has the most unstable shoreline?
Scandinavian Peninsula. Before the 18th century, it was thought in Sweden that sea levels were falling. On the initiative of Anders Celsius a number of marks were made in rock on different locations along the Swedish coast. In 1765 it was possible to conclude that it was not a lowering of sea levels but an uneven rise of land, later recognized as post-glacial rebound.
Which of the following European mountain ranges will rise the most in the next century?
Scandinavian Mountains. The whole Scandinavia experiences uplift as a result of post-glacial rebound. In northern Europe, this is clearly shown by the GPS data obtained by the BIFROST GPS network. The average uplift is less than 1cm/year, but it may accumulate to 400m during next 10,000 years.
Which desert has this famous "eye"?
Sahara. The Richat Structure in Mauritania, also known as the Eye of the Sahara, was interpreted as an asteroid impact structure, but no evidence of shock metamorphism has been found. Today, scientists believe that it is a huge (40 km in diameter) and deeply eroded geologic dome.
What is the typical source of pressure buildup inside a volcano?
Degassing of magma. The whole process begins when hot magma is lifted by convection to the magma chamber. As the pressure in the chamber is lower than deep in Earth's crust, the gas starts to release. Since degassed magma has lower density, it may then sink and be replaced with new one. This process may build up huge pressure of gases, eventually causing explosion.
Where is the famous Cave of the Crystals?
In Mexico. The cave near Naica, Mexico, was discovered in 2000 by miners. At that time, it was completely submerged. Today, the cave is accessible because the mining company's pumping operations keep it clear of water. Unfortunately, the crystals deteriorate in air, and soon may be lost.
What serves as a natural "tape recording" of the history of the Earth's magnetic field reversals?
Ocean floor. In the 1950s scientists discovered zebra-like pattern of the ocean floor magnetic polarity. It turned out that the stripes of rock parallel to the mid-ocean ridge crest alternate in magnetic polarity (normal-reversed-normal, etc.), suggesting that they were formed during different epochs documenting the normal and reversal episodes of the Earth's magnetic field.
Dry Falls is thought to be the greatest known waterfall that ever existed. Where is it?
In the United States. Dry Falls is a 3.5 mile long scalloped precipice in central Washington. According to the current geological model, catastrophic flooding channeled water over this 400-foot (120 m) rock face at the end of the last ice age. At this time, it is estimated that the flow of the falls was ten times the current flow of all the rivers in the world combined.
In moderate and cold climates, a tree gains one ring every year, which allows us to estimate its age. Where else we can estimate age in similar fashion?
At the bottom of the lake, sedimentation. At the bottom of some lakes the sediments stay very well preserved. Lamina lucida and lamina densa are created during the one year cycle. This fact can be used as lake's age estimation.