Polka "Polka". Nejedlý also writes that Václav Vladivoj Tomek also claims the Hradec Králové roots of a Polka. OED also suggests that the name may have been derived from the Czech "Polka" meaning "Polish woman" (feminine form corresponding to "Polák", a Pole). The word was widely introduced into the major European languages in the early 1840s. It should not be confused with the "polska", a Swedish dance with Polish roots (cf. polka-mazurka). A related dance is the redowa. Polkas almost always have a time signature. Folk music of Polka style appeared in written music about 1800. The beginning of the propagation
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