οἱ λίθοι κράξουσιν (Luke 19:40)
Flood Geology Challenge #5:
It is common to begin a history of the Appalachian Basin in the Cambrian Period. There are a few rifts that run through the basin, most notably the Rome Trough. It loses its importance as you go north into northern Pennsylvania and New York, but it is still present. The Cambrian through the lower Ordovician is noted by basal sandstones grading into the mostly dolomitized Knox Group. At the top of the Knox is a very regional unconformity. Across much of the continent, karsting is evident at this surface indicating subareal erosion.
Above the Knox Group are the extensive carbonates of the Trenton and Black River Formations. The upper Ordovician Trenton can be seen thickening and changing facies to the east into what was becoming a foreland basin as the Taconic Orogeny began. Above the Trenton, fine grained shales and siltstones grade into the reddish sandstones and shales of the Queenston Formation. The reddish color is diagnostic of terrestrial, or subareal deposition.
Above this is the Silurian Lockport Formation. It is the resistant rock at the top of the Niagara gorge and the rock the Falls are currently going over (see picture below). The Lockport is equivalent to the Niagaran Formation of the Michigan Basin which has been popularized by its impressive pinnacle reef formation and oil reservoirs. Above this is the Salina Group. It is a series of interbedded dolomites, limestones and evaporites. In places the Salina evaporites can be a few thousand feet thick.
View of Niagara Falls from the American side. At the top of the rock succession seen to the right of the falls is the resistant Lockport dolomite (photo by author).
The Devonian section lies above the Salina. Lower Devonian clastics and limestones grade into the Onondaga Limestone. In places there are reefs in the Onondaga that can be mapped along an old Devonian shelf edge. This is a different reef formation than the Niagaran which formed in front of, but parallel to, the Silurian shelf edge of the Michigan Basin. Above the Onondaga is the black shale of the Marcellus formation which grades into the gray shales, sandstones and thin carbonates of the upper Devonian.
Horn corals in the Devonian Onondaga Formation near Buffalo, New York. The ends are about the size of a quarter (photo by author).
Above the Devonian, much of the section is missing in the northern Appalachian Basin. I say this because there are trapped mini-basins that preserve Mississippian and Pennsylvanian sediments indicating it was deposited and later eroded away. In some of these mini-basins such as the Anthracite Basin around the towns of Scranton and Wilkes-Barre, coal beds can be found. There is outcrop evidence that much of the older formations were eroded away as the Alleghenian Orogeny occurred in the Pennsylvanian Period.
There are no Mesozoic or younger sediments preserved in the northern part of the basin. The only exception are the glacial deposits and formations of New York. These glaciers are responsible for carving out the Great Lakes and the Finger Lakes of upstate New York as well as depositing hundreds of feet of glacial till on the surface. In some places, huge rounded boulders of granite can be seen resting within a surrounding black shale. These two rock types should not occur together. The interpretation is that these boulders were carried down from the Canadian Shield and rounded by the transport within the glaciers that carried them. When the glaciers melted, the boulders were dropped (see photo below).
Forest near Buffalo, NY. The waterfall is running over the Devonian Rhinestreet Shale. The boulders on the left are granite and interpreted as glacial erratics. As the glaciers retreated at the end of the ice age, they left these boulders behind (photo by author).
It should be evident that there are multiple sedimentary packages and features at different times in this history of the northern Appalachian Basin that cannot result from turbulent water. The Knox unconformity requires it be above water for a time. The red beds of the Queenston were deposited in a river to delta environment. The Silurian reefs require tranquil water. The salt demands a shallow restricted basin and time to evaporate. The Devonian reefs indicate going back to a stable quiet carbonate platform. The coal deposits indicate a swampy setting at sea level. The Paleozoic section of the basin shows evidence of many times where the seas were very quiet, very restricted, or not present at all. This sequence of rocks is incompatible with an interpretation that suggests they were all deposited in a year-long catastrophic global Flood.
Furthermore, there is evidence from well logs and seismic data that there was a complicated history to the basin even before the Cambrian Period. Wells that hit “basement” rock encounter metamorphic rocks like quartzite, schist and gneiss. Steep bed dips and thrust faults can be seen on seismic data, but the boundary between the Pre-Cambrian and the Cambrian appears fairly flat. This suggests that there were sedimentary layers deposited in the Pre-Cambrian that were later caught up what is called the Grenville Orogeny, metamorphosed and later eroded flat. These Grenville Mountains were in a similar setting to the present day Appalachians. So, if one complete rifting to collision cycle (Wilson Cycle) is too complex to be the result of the Flood, then we can certainly rule out two.