Polka Polka The polka is originally a Czech dance and genre of dance music familiar throughout Europe and the Americas. It originated in the middle of the 19th century in Bohemia, now part of the Czech Republic. The polka remains a popular folk music genre in many European countries, and is performed by folk artists in the Czech Republic, Germany, Austria, Slovenia, Switzerland, and Finland, and to a lesser extent in Poland, Latvia, Lithuania, the Netherlands, Hungary, Italy, Ukraine, Romania, Belarus, Russia, and Slovakia. Local varieties of this dance are also found in the Nordic countries, Spain's Basque Country, the United
Types of volcanic eruptions Types of volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions. The most well-observed are magmatic eruptions, which involve the decompression of gas within magma that