From eyewitness reports, photographs, and monitoring equipment, it is known that this whole deposit formed in just three hours, from 9 pm to midnight on 12 June 1980.1
September 24, 2019- updated 09/25/2026
RAPID LAYERING
One of the most striking lessons from the 1980 eruption of Mount St. Helens is how rapidly finely layered deposits can form under catastrophic conditions.
On June 12, 1980, another explosive eruption sent fast-moving pyroclastic flows down the volcano’s north side. The U.S. Geological Survey confirms that the June 12 eruption produced extensive pyroclastic-flow deposits, part of a series of explosive events following the major May 18 eruption.¹
At one location, the June 12 event produced a deposit approximately 25 feet thick containing numerous thin laminae and beds. Creationist geologist Steven Austin reported that this deposit accumulated in less than a day, while later descriptions place the principal deposition within only a few hours.²
The significance is not merely the deposit’s thickness. It is the fine internal layering.
Instead of producing one thoroughly mixed mass of volcanic debris, the fast-moving flow sorted particles into numerous distinct layers. Some laminae were only millimeters thick while other beds were much thicker.
RAPID FLOW CAN PRODUCE FINE LAYERS
Fine lamination can sometimes give the visual impression of extremely slow deposition. In certain geological environments, especially true annual varves, alternating layers really can represent seasonal cycles.
But the key lesson from Mount St. Helens is that fine layering alone does not establish slow deposition.
Here, finely layered deposits formed during a known modern catastrophe whose timing was directly observed. The process involved pyroclastic density currents, hot mixtures of volcanic ash, rock fragments, and gas moving rapidly across the landscape. USGS studies document pyroclastic-flow deposits from the June 12 eruption and subsequent detailed field investigations of those deposits.¹ Mount St. Helens therefore provides a modern example that catastrophic flows can produce considerable thicknesses of finely stratified material very rapidly.
LABORATORY EXPERIMENTS SHOW THE SAME SORTING PROCESS
Experiments involving mixtures of different grain sizes have also demonstrated that lamination can develop during continuous sediment transport.
Pierre Julien, Yongqiang Lan, and Guy Berthault conducted experiments with heterogeneous mixtures of quartz, limestone, and coal particles. They found that moving mixtures could spontaneously sort as smaller particles fell between larger rolling particles.
They concluded:
“Superposed strata are not necessarily identical to successive sedimentary layers.”³
Their experiments produced lamination under continuous deposition rather than requiring a long pause between every visible layer.³ Later flume experiments likewise demonstrated that stratification could develop under steady flowing conditions and continuous sediment supply.
WHAT MOUNT ST. HELENS ACTUALLY DEMONSTRATED
Mount St. Helens did not demonstrate that every laminated geological deposit formed rapidly. What it demonstrated is equally important: Thin layers cannot automatically be used as a clock.
The rate at which layered deposits formed must be established from evidence about the depositional environment, rather than inferred merely from the number or thinness of the layers. Before 1980, no geologist could stand beside these particular deposits and know their formation time merely by counting their laminae. In this case we know the time because the event occurred within recorded history.
Approximately 25 feet of finely layered material formed in only hours.
That observation deserves serious consideration whenever enormous spans of geological time are inferred primarily from the presence of finely laminated deposits elsewhere.
Sources
- U.S. Geological Survey, Database for Geologic Maps of Pyroclastic-Flow and Related Deposits of the 1980 Eruptions of Mount St. Helens, Washington. The USGS documents pyroclastic-flow deposits from eruptions on May 18, May 25, June 12, July 22, August 7, and October 16–18, 1980.
https://pubs.usgs.gov/publication/ds1054 - Steven A. Austin, “Mount St. Helens and Catastrophism,” Institute for Creation Research. Austin reports a June 12 deposit approximately 25 feet thick containing numerous thin laminae and beds that accumulated in less than one day.
https://www.icr.org/articles/print/261 - Pierre Y. Julien, Yongqiang Lan, and Guy Berthault, “Experiments on Stratification of Heterogeneous Sand Mixtures,” originally published in Bulletin of the Geological Society of France, Vol. 164, No. 5, 1993, pp. 649–660; English version published in Creation Ex Nihilo Technical Journal, Vol. 8, No. 1, 1994, pp. 37–50.
https://creation.com/en/articles/experiments-on-stratification-of-heterogeneous-sand-mixtures
http://www.wasdarwinright.com/geologicalcolumn.htm
