Volcanoes shaped our planet
Fiery catastrophe greater in the past
Swirling clouds of ash and dust belched high above the Andes, disrupting air traffic and settling over the landscape. The sudden eruption of the Puyehue volcano in Chile in June 2011 demonstrated the power of untamed energy beneath the earth. Volcanic eruptions can devastate the countryside with burning lava, deadly ash and destructive mud. In fact, volcanoes are to blame for many of the world’s worst natural disasters.
But volcanoes also have their good points. Some of the most beautiful mountains are volcanoes, such as Mount Fuji in Japan. Also, the ash deposited by volcanoes forms fertile soil, outstanding for agriculture.
Right now at least 20 volcanoes are erupting around the globe,1 concentrated on the boundaries between the earth’s crustal plates. The Pacific plate has so many volcanoes around its edge that it has been called the ‘Ring of Fire’.
Deadly fire clouds
During a volcanic eruption, clouds of superheated gas and broken rock, called tephra, can surge down the flanks and blast across the countryside. Dubbed ‘pyroclastic flows’,2 these ash clouds are so hot that they glow red in the dark.3 They skim the ground with the speed of a jetliner, destroying everything in their path.
On 8 May 1902, Mount Pelêe erupted on the island of Martinique in the Caribbean, producing a pyroclastic flow. Within minutes, the deadly cloud engulfed the nearby town of St Pierre, killing almost the entire population of some 30,000 people.
American volcano lessons
Mount St Helens volcano in Washington State, north-west USA, would be one of the most studied volcanoes on earth. On 18 May 1980, at 8:32 am, a surge of magma deep underground triggered an avalanche on the mountainside. Like a cork popped from a bottle of soda, the pressure inside the mountain unleashed the deadliest and costliest volcanic disaster in the history of the US: 57 lives were lost.
One remarkable effect of the Mount St Helens eruptions is that geologists are now more accepting of catastrophic geologic processes. Previously they were wedded to the idea that geological features formed slowly over millions of years. But their ideas changed after they saw that thick beds of ash, deposited in less than an hour, displayed fine laminations. That proved that long periods of time are not essential for fine layers to form.
Some of the large canyons in the area, now containing small streams, did not take ages to erode but were carved by catastrophic mudflows in less than a day. Rocky surfaces with grooves and striations were not chiselled by glaciers, but scraped by rock blasted along the ground.
Radioactive dating of rock that formed since the 1980 eruption gave ‘ages’ of hundreds of thousands, even millions of years, showing that the fundamental assumptions behind radioactive-dating were wrong.4
Mount St Helens ejected 1 km³ (0.24 cubic miles) of ash and dust from its vent, yet that was a small eruption compared with the ejecta from volcanoes of the distant past. For example, the ash deposited by the post-Flood5 Huckleberry Ridge eruption in Yellowstone Park, Wyoming, was 2,500 times greater than for Mount St Helens.
Volcanic activity on the earth has been tapering off from a time in the past when eruptions were much greater.6 During Noah’s Flood, 4,500 years ago, water not only rained from the heavens but also burst from underground from “the fountains of the great deep” (Genesis 7:11). These fractures and upheavals in the earth’s crust caused great volcanic activity. It was many hundreds of years after the Flood ended before the earth settled down.
Sometimes, after a huge volume of magma erupts from a volcano, the overlying ground will collapse into the empty magma chamber to form a caldera. This is a circular depression on the surface of the earth that has a flat floor and steep walls. After its collapse, more lava is often forced up through cracks around the rim.
Calderas can range in diameter from a few kilometres to more than 50 kilometres. Water often fills the depression to form a lake, as with beautiful Lake Rotorua in New Zealand, created by a volcanic explosion after Noah’s Flood.7
Huge eruptions in the past
During Noah’s Flood some volcanic eruptions covered enormous areas, such as the Columbia River Basalt Group in north-western USA. Here, as many as 300 individual lava flows engulfed some 163,000 km² (63,000 sq. miles) of the countryside to a depth of more than 1.8 km (1.1 miles).8 The lava gushing from the earth was so hot and runny that it flowed across the landscape for vast distances. The flood waters were still around when the eruptions took place, and they deposited sediment, as well as wood (now petrified) and gravel, between some of the lava flows. The individual flows followed each other so quickly that there was not much erosion between them. But when the lava finally stopped, as the waters of Noah’s Flood receded into the ocean they eroded deep valleys into the basalt complex.8
These enormous volcanic deposits have been called ‘Large Igneous Provinces’ (or LIPs). Contrasting with today’s volcanoes, LIPs are usually found within the earth’s plates instead of along their edges.
Because LIPs are so much larger9 than the volcanoes we see today, long-age geologists are puzzled. What could have produced the titanic volume of magma, and how was so much lava erupted so quickly? They suggest that mantle plumes, large upward movements of hot rock from deep in the earth, were responsible. But the puzzle remains. What caused the plumes? We do not see plumes of this magnitude beneath volcanoes today. However, enormous volcanic eruptions like this are to be expected from Noah’s Flood catastrophe, which impacted the deep interior of the earth.10
Next time we see a volcano in the news spraying fountains of red-hot lava into the air and blackening the sky, we should be thankful that these eruptions are small compared to the mammoth eruptions during Noah’s Flood. That was the greatest catastrophe of water and fire this world has ever seen.
Shapes made by different lavas
Molten rock, while it is inside the earth, is called magma, but once it erupts onto the surface is called lava. Rocks that harden from magma are called plutonic (after the Greek god of the underworld, Pluto), and usually have large crystals, while rocks hardening from lava are called volcanic, and usually have very fine crystals. The composition of the magma depends on the source rock and how much of it melted.
Magma that is rich in magnesium and iron is described as mafic. It is highly fluid (thin, runny) and gushes out of fissures in the ground at over 1,000 °C. This lava solidifies into a black rock called basalt (if the magma cools inside the earth, it forms gabbro). Like a fountain, basaltic eruptions in Hawaii and Iceland spray red-hot lava into the air, which then flows in glowing red streams into nearby valleys or the ocean. These eruptions are placid and predictable, and popular as tourist attractions. The lava forms large, flat cones called shield volcanoes.
Magma with less iron and magnesium is less fluid, and can solidify into a grey rock called diorite. If this type of magma becomes lava, it will solidify into andesite. Eruptions can be violent and build steep cones. Andesite was named after the Andes Mountains in South America which mostly have andesitic composition.
With even less iron and magnesium the magma is thick and tacky. It is called felsic magma because it is rich in elements that produce feldspar and silica minerals. Felsic magma can erupt explosively or ooze like toothpaste to form a blob. The lava solidifies into a yellow, pink or pale-grey rock called rhyolite (the plutonic equivalent is granite). Mt St Helens erupted into a lava dome of dacite, between andesite and rhyolite in composition.
References and notes
- How many active volcanoes are there in the world? volcano.si.edu/faq/index.cfm?faq=03, accessed 15 September 2011. Return to text.
- From the Greek: πῦρ pyr=fire, κλαστός klastôs=broken in pieces. Return to text.
- At temperatures of 1,000 °C (1,830 °F) or more. Return to text.
- Swenson, K., Radio-dating in Rubble: The lava dome at Mount St Helens debunks dating methods, Creation 23(3):23–25, 2001; creation.com/radio-dating-in-rubble. Return to text.
- Uniformitarian geologists claim the Huckleberry Ridge eruption occurred 2.1 million years ago, but that was actually the early post-Flood era. Return to text.
- Austin, S.A., The declining power of post-Flood volcanoes, Acts & Facts 27(8), 1998; icr.org/article/declining-power-post-flood-volcanoes/. Return to text.
- The eruption of Rotorua and the formation of the caldera are quoted as occurring some 200,000 years ago according to uniformitarian assumptions, but in real time this is within the post-Flood era. Return to text.
- The total volume was more than 170,000 km³. Woodmorappe, J. and Oard, M.J., Field studies in the Columbia River basalt, Northwest USA, Journal of Creation 16(1):103–110, April 2002. Return to text.
- Often covering an area of several million km² and having a volume of lava of a million km³. Return to text.
- Baumgardner, J.R., Runaway subduction as the driving mechanism for the Genesis Flood; in: Walsh, R.E. (Ed.), Proceedings of the Third International Conference on Creationism, Technical Symposium Sessions, Creation Science Fellowship, Pittsburgh, pp. 63–75, 1994. Return to text.