Figure 1 is from the raised walkway through Hidden Valley in Mirima National Park, Kununurra, WA. You can see the steep escarpment in the rock outcrop ahead, which rises some 30 metres above the floor of the valley. It is part of a deposit that is many hundreds of metres thick.
The sediment you can see was deposited during Noah’s Flood as the floodwaters were rising, and it covered a huge area in that region. This hill is part of a small outcrop near Kununurra, which is all that remains (in this area) after the rest of the sedimentary deposit was eroded away. Outcrops of this sediment are found in other areas in this region of WA and NT. The waters of Noah’s Flood eroded this huge sediment deposit as they were receding from the Australian continent into the oceans.
This sedimentary deposit is classified by uniformitarian geologists as Upper Devonian. They assign a date to that of 360 million years ago, but from a biblical perspective it was deposited by the raging floodwaters as they were rising, a month or two before they covered the whole earth. This timing is indicated in the biblical geological model as the late Ascending phase. Evidence of raging waters is visible in the rock outcrop. First, let’s look at how sediment is deposited in strata, and at a remarkable feature called cross-beds.
Figure 2 shows a diagram of some horizontal strata that have lines cutting across them at an angle, forming cross beds. The thinking behind how cross beds form is as follows. The water containing lots of sediments flows from the left. The surface of this example shows two ripples. (If the ripples are large, they are called dunes.) The front of the ripples faces away from the direction of the water flow. What happens is that the sediment drops out of the water at the front edge of each dune because the flow of water is reduced at this point.
As the sediment is deposited, the front edge of each dune grows sideways to the right forming cross beds in the strata. These cross beds are called foresets because they form at the front of the dune. Figure 2 shows two dunes on the surface of the sediment but there would be multiple dunes where the sediment is being deposited. Figure 2 shows six strata, of which the top two are incomplete because they are still forming sideways. For the sediment to accumulate there needs to be enough depth of water for it to deposit. In other words, a thick deposit with multiple strata indicates that the water level is continuing to rise.
In figure 3 I have added lines to the rock outcrop of figure 1, illustrating the evidence of the raging waters of Noah’s Flood. The sediment was deposited in strata from flowing water. The straight lines indicate the strata, which originally would have been horizontal. However, they dip downwards to the left, indicating that the area was tilted by geological forces after all the sediment had been deposited.
The single stratum at the bottom looks to be about 5 metres thick, which is thicker than the two strata that sit on top. The thickness of the strata indicates that there was a considerable depth of water flowing across the area depositing the sediment. For the bottom stratum the depth of water would have been much more than 5 metres—perhaps double that thickness.
Notice the curved lines that slope downwards to the right. These cut across the strata, which is why they are called cross beds. There are many such lines cutting across the strata, but I have only highlighted two. Notice that the bottom of the cross beds curve until they run almost parallel to the bottom of the strata. This is the way the sediment was deposited from the water as the water was flowing from the left to the right, dropping sediment. Notice that the tops of the cross beds have been cut off by the stratum that sits above it. This indicates that as the sediment above was washed in, the flow of water eroded the top of the sediment layer underneath.
The presence of these beds of sediment in Mirima National Park near Kununurra provides compelling evidence of the enormity of the catastrophic water flows that raged over the region during Noah’s Flood. The volume of the sediment indicates that there was great erosion occurring on other parts of the earth and transporting sediment into the area. The consistent size distribution of the sand comprising the sediment indicates that it was sorted by water transport. The thickness of the strata indicates that the depth of water flowing into the area was enormous. The presence of cross beds indicates that the water was flowing. We would expect the sediment to cover a vast area, which in fact it does. The vast erosion points to the erosive effects of the receding waters of the Flood from the time they covered the whole area until they eventually flowed into the oceans and the land was dry. The small amount of eroded sediment at the bottom of the steep escarpments indicates that the erosion occurred not that long ago, which is consistent with the timing of Noah’s Flood, some 4,500 years ago.
These are some of the amazing features recorded in this sandstone outcrop that point to the catastrophic effects of Noahs’ Flood. This event explains the fossils and washes away the idea of millions of years.
Berend de Boer
Great explanation! Had to read it slowly, but now I finally understand the word “cross bed”. Much appreciated.
Andrew Snowdon
Do you think multiple strata can form simultaneously in an off-set fashion? Are the mechanisms that can form series of strata, multiple crustal movements producing tsunamis, perhaps mediated by slumping or would normal tides play a part? That is, what might cause the succession of sedimentary deposits?
Tas Walker responds: Continuous sedimentation by water carrying sediment into a larger body of water will deposit the sediment sideways on the bottom. It can be deposited in layers/strata, and these will grow sideways at multiple levels st the same time. Density flows from underwater avalanches producing sediment-rich slurry deposit multiple layers.
I gather that this sedimentation is very different from river flooding because I recall Ron Neller saying “Instantaneous deposits from flooding rivers are typically only millimetres or centimetres deep, not the metres or tens of metres…” This must mean we are talking about a process with no modern analogue. Perhaps it is more akin to a mud flow?
Tas Walker responds: Deposits from a single event would only be thin. However, if the sediment is being deposited into deeper water it would be thicker.
Given the speed of water and forces involved, do you ever see evidence of cavitation, or can that only be detected when it is happening?
Tas Walker responds: Cavitation occurs at certain water depths and flows where the local static water pressure is less than the water vapor pressure. Cavitation destroys rock, and would be one of the mechanisms during the Flood which eroded rock and produced the abundant sediment we see deposited on the continents.