**2. Polygenetic vs. monogenetic systems**

Volcano types are commonly distinguished along their appearance, volume, and the time required for their formation. Polygenetic volcanic systems are characteristically long-lived volcanoes with a stable melt source and conduit system. Individual eruptions occur in diverse eruption styles, but they activate many times over the total lifespan of the volcano. As a result, a large volcanic edifice will build up that is surrounded by a broad ring plain where mostly valley-filling pyroclastic density currents, hot and cold reworked equivalent of them, accumulate alongside with landscapedraping ash fall beds. Further away we are from the source volcano, the higher the

*Introductory Chapter: Linking Modern and Ancient Volcanic Successions DOI: http://dx.doi.org/10.5772/intechopen.110313*

#### **Figure 2.**

*Harat Rahat in Saudi Arabia is a typical mature monogenetic volcanic field with several silicic eruptive centers forming maars, small calderas, and lava domes such as the Holocene Um Rgaibah. The trachytic block-and-ash fan is clearly distinct on a Sentinel Highlight Optimized satellite image.*

influence of the background sedimentation, resulting in developing extensive volcaniclastic sedimentary basins. On the contrary, small-volume and short-lived, so called "one shot," eruptions are commonly defined as monogenetic volcanoes [11]. They mostly form complex groups of volcanoes, a volcanic field where the primary volcanic deposits (e.g., directly fed by an eruption) are dispersed over large (100 s km2 ) areas (**Figure 2**). While each volcano erupts only once, their eruption record could show great variation of eruption styles as a function of the interaction between the magmatic and external (mostly water) impacts on the individual explosive eruptions. Overall, if the volcanic field is long lived (million years scale), significant volumes of inter-volcano volcaniclastic deposits can accumulate. Over time, volcanic fields can reach mature stages when they can feed from magmas that have evolved over time and produce simple silicic explosive volcanoes such as known from many volcanic fields from the Arabian Peninsula (**Figure 2**).
