A supervolcano is classified as a volcano with an eruption magnitude of 8, the largest value on the Volcanic Explosivity Index (VEI) where the volume of deposits for that eruption is greater than 1,000 cubic kilometers (240 cubic miles).
In ancient Norse mythology and cosmology, Yggdrasil is an immense tree that sprang forth in the primordial void of Ginnungagap, unifying the 9 worlds of Asgard, Álfheimr/Ljósálfheimr, Niðavellir/Svartálfaheimr, Midgard (Earth), Jötunheimr/Útgarðr, Vanaheim, Niflheim, Muspelheim & Hel.
Hertfordshire is a county in southern England that sits directly above London. With occupation stretching as far back as the Mesolithic period, Hertfordshire is rich in a variety of historical sites, monuments and ancient ruins waiting for you to explore.
A cave is a hollow place in the ground, specifically a natural underground space large enough for a human to enter. Caves form naturally by geothermal activities or the weathering of rock and often extend deep underground.