This is the online edition of In the Beginning: Compelling Evidence for Creation and the Flood
(7th Edition) by Dr. Walt Brown. The online version of the book is designed to be read online.
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Examples of Liquefaction
Quicksand. Quicksand is a simple example of liquefaction. Spring-fed water flowing up through sand creates quicksand. The upward flowing water lifts the sand grains very slightly, surrounding each grain with a thin film of water. This cushioning gives quicksand, and other liquefied sediments, a spongy, fluidlike texture.3
Contrary to popular belief and Hollywood films, a person or animal stepping into deep quicksand will not sink out of sight forever. They will quickly sink in—but only so far. Then they will be lifted, or buoyed up, by a force equal to the weight of the sand and water displaced. The more they sink in, the greater the lifting force. Buoyancy forces also lift a person floating in a swimming pool. However, quicksand’s buoyancy is almost twice that of water, because the weight of the displaced sand and water is almost twice that of water alone. As we will see, fluidlike sediments produced a buoyancy that largely explains why fossils show a degree of vertical sorting and why sedimentary rocks all over the world are typically so sharply layered.
Earthquakes. Liquefaction is frequently seen during, and even minutes after, earthquakes. During the Alaskan Good Friday earthquake of 1964, liquefaction caused most of the destruction within Anchorage, Alaska. Much of the damage during the San Francisco earthquake of 1989 resulted from liquefaction. Although geologists can describe the consequences of liquefaction, few seem to understand why it happens. Levin describes it as follows:
Often during earthquakes, fine-grained water-saturated sediments may lose their former strength and form into a thick mobile mudlike material. The process is called liquefaction. The liquefied sediment not only moves about beneath the surface but may also rise through fissures and “erupt” as mud boils and mud “volcanoes.” 4
Strahler says that in a severe earthquake:
... the ground shaking reduces the strength of earth material on which heavy structures rest. Parts of many major cities, particularly port cities, have been built on naturally occurring bodies of soft, unconsolidated clay-rich sediment (such as the delta deposits of a river) or on filled areas in which large amounts of loose earth materials have been dumped to build up the land level. These water-saturated deposits often experience a change in property known as liquefaction when shaken by an earthquake. The material loses strength to the degree that it becomes a highly fluid mud, incapable of supporting buildings, which show severe tilting or collapse.5
These are accurate descriptions of liquefaction, but they do not explain why it occurs. When we understand the mechanics of liquefaction, we will see that liquefaction once occurred continuously and globally for weeks or months during the flood.
Visualize a box filled with many rocks. If the box were so full that you could not quite close its lid, you would shake the box, so the rocks settled into a denser packing arrangement. Now repeat this thought experiment, only this time all space between the rocks is filled with water. As you shake the box and the rocks settle into a denser arrangement, water will be forced up to the top by the “falling” rocks. If the box is tall, many rocks will settle, so the force of the rising water will increase. The taller column of rocks will also provide greater resistance to the upward flow, increasing the water’s pressure even more. Water pressure will exert a lifting force on the rocks for as long as the upward flow continues.6
This is similar to an earthquake in a region having loose, water-saturated sediments. Once upward-flowing water lifts the topmost sediments, weight is removed from the sediments below. The upward flowing water can then lift the second level of sediments. This, in turn, unburdens the particles beneath them, etc. The particles are no longer in solid-to-solid contact, but are suspended in and lubricated by water, so they can easily slip by each other.
Wave-Loading—A Small Example. You are walking barefooted along the beach. As each wave comes in, water rises from the bottom of your feet to your knees. When the wave returns to the sea, the sand beneath your feet becomes loose and mushy. As your feet sink in, walking becomes difficult. This temporarily mushy sand, familiar to most of us, is a small example of liquefaction.
Why does this happen? At the height of each wave, water is forced down into the sand. As the wave returns to the ocean, the water forced into the sand gushes back out. In doing so, it lifts the topmost sand particles, forming the mushy mixture.
If you submerged yourself face down under breaking waves but just above the seafloor, you would see sand particles rise slightly above the floor as each wave trough approached. Water just above the sand floor also moves back and forth horizontally with each wave cycle. Fortunately, the current moves toward the beach as liquefaction lifts sand particles above the floor. So, sand particles are continually nudged upslope, toward the beach. If this did not happen, beaches would not be sandy.7
Wave-Loading—A Medium-Sized Example. During a storm, as a large wave passes over a pipe buried offshore, water pressure increases above it. This forces more water into the porous sediments surrounding the pipe. As the wave peak passes and the wave trough approaches, pressure over the pipe drops, and the stored, high-pressure water in the sediments flows upward. This lifts the sediments and causes liquefaction. The buried pipe, “floating” upward, sometimes breaks.8
Wave-Loading—A Large Example. On 18 November 1929, an earthquake struck the continental slope off the coast of Newfoundland. Minutes later, transatlantic phone cables began breaking sequentially, farther and farther downslope, away from the epicenter. Twelve cables were snapped in a total of 28 places. Exact times and locations were recorded for each break. Investigators suggested that a 60-mile-per-hour current of muddy water swept 400 miles down the continental slope from the earthquake’s epicenter, snapping the cables.9
This event intrigued geologists. If thick muddy flows could travel that fast and far, they could erode long submarine canyons and do other geological work. Such hypothetical flows, called turbidity currents, now constitute a large field of study within geology.60-mile-per-hour, turbidity-current explanation:
- water resistance prevents even conventional nuclear-powered submarines from traveling nearly that fast,
- the ocean floor in that area off the coast of Newfoundland slopes less than 2 degrees,
- some broken cables were upslope from the earthquake’s epicenter, and
- nothing approaching a 400-mile landslide has ever been observed—let alone on a 2 degree slope or underwater.
Instead, a large wave, a tsunami,10 would have rapidly radiated out from the earthquake’s epicenter. Below the expanding wave, sediments on the seafloor would have partially liquefied, allowing them to flow downhill.11 This sediment flow loaded and eventually snapped only those cable segments that were perpendicular to the downhill flow. Other details support this explanation.
We can now see that liquefaction occurs whenever water is forced up through loose sediments with enough pressure to lift the topmost sedimentary particles. Now let’s look at a gigantic example of liquefaction, caused by many weeks of global wave-loading.