Polka in the United States Polka in the United States Polka in the United States refers to polka—a music and dance style that originated in Europe in the 1830s and came to American society when people immigrated from Eastern Europe. A fast style in 2/4 time, and often associated with the pre–World War II era, polka remains a dynamic "niche" music in America. Several polka genres exist in the United States, each with its own unique characteristics and performers. Though these polka genres vary, all are unified in the expression of ethnicity by performers and participants. Polka enthusiasts gather to enjoy their love of the
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