Sunday, November 6, 2022

Flood Geology of Mackinac Island

And the waters prevailed, and were increased greatly upon the earth...
Genesis 7:18

"Mackinac Island exposes rocks from two of the earliest megasequences of the Flood, the Tippecanoe and the Kaskaskia
The Kaskaskia is the younger of the two and lies on top of the Tippecanoe. Globally, these layers are filled with shallow-water marine fossils, since at that point the floodwaters had not yet begun to cover the dry land.
 
Some of these rocks are visible near the center of the island on the highest point. Referred to as the Ancient Island, its peak is about 275 feet above today’s Lake Huron. 
Here, near the War of 1812-era Fort Holmes, some of the lower
Kaskaskia
sediments are exposed, known as the Devonian Bois Blanc Formation. Below this half-mile-long hill and across most of the island reside carbonate rocks of the upper Tippecanoe Megasequence (Silurian St. Ignace Dolomite). 
These two sedimentary layers make up the bulk of the island and were most likely deposited within the first 40 days of the Flood. They were exposed as the floodwaters receded and were further sculpted by the post-Flood Ice Age.
 
Scattered around the island are several prominent “sea” stacks composed of broken and angular pieces of rock. These resistant spires, stacks, arches, and even a cave are composed of Mackinac
Breccia.
 
Breccia is made up of broken, angular chunks of rock melded together
*These stacks formed in a manner similar to a sinkhole and were the product of salt dissolution and collapse. In this case, the sediments composing the broken pieces were deposited on top of the St. Ignace Dolomite. Below this dolomite lie earlier Flood rocks that are rich in salt
 
During the Flood’s continued advance, water was forced into the ground and dissolved some of the salt. With no support from below, the overlying sediments collapsed, dropping fragments from above into the vacant cavity. Swirling groundwater cemented these broken fragments together.
 
As the receding Flood stripped away the surface layers, the breccia
stacks
were left behind as “sea” spires. Glacial lake water further carved some of these into caves such as Skull Cave and arches such Arch Rock.
 
Native Americans referred to the island as Michilimackinac, or “place of the great turtle,” because in profile the island resembles a turtle’s back. 
This appearance is due to erosion during the two primary Ice Age lake levels, the older Lake Algonquin and the younger Lake Nipissing
 
The Ancient Island was all that was exposed above the water line when Lake Algonquin crested at over 230 feet above the present lake level. Its waves carved a steep cliff marking the edge.
As the lake levels further dropped, over two dozen successive shoreline ridges were formed prior to the formation of Lake Nipissing
 
This younger level was only about 50 feet above the level of Lake Huron today. It also formed a 45- to 50-foot wave-cut cliff that nearly circles the island. Fort Mackinac was established on this cliff in 1780, as was the Grand Hotel in 1887.
 
The two prominent wave-cut cliffs and the numerous shoreline ridges preserve evidence of the many changing Ice Age lake levels. These features always seem to be present wherever Ice Age lakes resided.....In fact, these landforms can occur in just a few weeks. Creation scientists calculate that the Ice Age lasted about 500 to 700 years after the Flood. The development of these landforms easily fits within the biblical timeline." ICR