User:Dermot Mac Flannchaidh/Theories

My theories.

Lake Hylia as a volcano
Lake Hylia may be a volcano &mdash; not necessarily an active volcano, but a volcano nonetheless. But unlike the complex volcanism of Death Mountain, Lake Hylia is most likely a maar. Evidence for this includes its maar-like punchbowl shape &mdash; vaguely circular shoreline, steep lake walls, and great depth, and the fact that its greatest depth at the center goes down even deeper below the lakebed into the Water Temple, a cross-section of which would probably resemble the remnants of a volcanic pipe.

It is possible that Lake Hylia is still active, but that its largely limited to limnic eruptions. In a limnic eruption, the deepest waters become increasingly saturated with carbon dioxide gas from its volcanic source. When the deep waters become too saturated, the lake overturns and releases all the gas at once. In the real world, such an eruption at Cameroon's Lake Nyos in 1986 destroyed surrounding villages, killing 1700 people and 3500 livestock. After that disaster, volcanologists started installing deep water pipes to continually fountain the gas so it doesn't have a chance to oversaturate the water.

It may be that Lake Hylia's Water Temple and/or Lanayru Spring already serve this function, as the lake's water is already constantly filtered to keep it pure. It remains pure enough to supply Castle Town with drinking water. If Lake Hylia were active and limited to limnic eruptions, this would effectively render the volcano inactive as it would be unable to erupt either way.

Hyrule as a rift valley basin
If indeed both Death Mountain and Lake Hylia are volcanoes, it may be safe to guess that much of Hyrule's geology is of volcanic origin. Additionally, its appearance and layout in gives the impression that it is made up of horst and graben terrain. A graben is an area of land subsidence caused when the crust spreads and becomes thinner. In places like the Great Rift Valley and in Iceland, this creates subsiding volcanic lowlands nestled against swollen volcanic highlands.

There is evidence in Twilight Princess that such a process could have progressed somewhat since. Indeed, Hyrule's landscape is shorn by gaping chasms, and the floor of both Zora's River and Lake Hylia appear to be sinking to lower elevations relative to the surrounding countryside. This could have influenced the change in the course of Zora's River since Ocarina of Time; rather than the river changing course and eroding a deep gorge in such a relatively short period of time, the gorge may have cracked open first and the river started flowing into it. Lake Hylia may have genuinely formed as a volcano, but is also located in a sinking graben.

If Hyrule is a rift valley basin, it is also possible that most of its land is significantly below sea level, as seen in other rift basins located inland from the sea. When the Great Flood occurs in the Adult Timeline, it may not have been rain alone that inundated the kingdom, but the break of a natural dam that allowed the ocean's waters to fill the basin, leaving only its highest points as islands in the Great Sea. Magic alone kept Hyrule below dry and frozen in time. Magic aside, this is not without precedent, as the entire Mediterranean Sea has dried up and refilled multiple times in ancient prehistory in a similar manner. However, during these dry periods (part of what is called the Messinian salinity crisis), the Mediterranean Basin was mostly a salty desert, not unlike Death Valley (or perhaps the Gerudo Desert or Lanayru Desert).

Spectacle Rock as a volcanic plug
Spectacle Rock superficially appears to be a lava spine, which is lava that solidifies first and gradually extrudes itself from a volcano's vent. Lava spines have been witnessed in association with volcanic eruptions at Mont Pelée and Mount Saint Helens. However, lava spines are inherently unstable and usually imminently collapse after extrusion. Considering Spectacle Rock seems to have a primordial age and even has an ancient Fire Temple located inside it, it seems unlikely that it is a lava spine.

Spectacle Rock may actually be a volcanic plug, which can be shaped similarly to a lava spine, but is actually much, much older, often as old as hundreds of millions of years. Volcanic plugs are actually the remnants of the central magma chambers of volcanoes, and appear on the land only after the rest of the volcano has already crumbled away after millions of years. The magma chamber cools more slowly and under greater pressure, forming an extremely hard rock that is naturally very resistant to erosion. As such, volcanic plugs can stand out above surrounding countryside long after volcanism in a region has ended.

Hyrule was created by the three Golden Goddesses, and the land's actual age is not clear, but it seems unlikely that the Goddesses created it all in just a matter of days. As such, Spectacle Rock could actually be a remnant of a long-extinct prehistoric volcano, and remained in place even as the younger Death Mountain eventually started forming at roughly the same location.

Admittedly, this theory stretches the bounds of realism, as it is difficult to imagine Spectacle Rock surviving repeat violent pyroclastic explosions unscathed. Ultimately, the true nature of Spectacle Rock may be at least partly magical.

Lake Hylia as a fish-free anoxic lake
The reason Lake Hylia proper (at least in ) has no fish, may be because of the way the water is purified &mdash; they are anoxic waters. Fish can't breathe normal air, but they still need oxygen to survive, and this comes from oxygen dissolved in water. The Lake Hylia filtration process purifies it, but also removes its dissolved oxygen, leaving the lake desolate of aquatic life. The Zoras don't live in the lake, but they can visit there because they have technology to allow them to breathe underwater regardless of dissolved oxygen content, and Link's Zora armor uses the same technology. Without this technology, a human like Link would also easily die from decompression sickness alone, whether or not there is dissolved oxygen in the water.