The Spreading Ocean FloorIn the years 1892-1910, my fossil collecting was confined to formations of the Paleozoic Era, from the Carboniferous Period down into the Cambrian. These deposits were in the Midwestern States, covering an area around the Great Lakes, extending westward to both sides of the present Mississippi River.
The absence of Mesozoic and Cenozoic deposits in this area seemed most peculiar, as they were abundantly represented in the far West. I consulted scientists, but they gave me no explanation. The fossils I was collecting were all marine invertebrates, no reptiles or mammals, as were common in the far West. Apparently, the life of one hundred fifty million years more or less had vanished completely.
An explanation of this appears in the recent account of movement of the Earth's crust along the underlying mantle, which like a giant bulldozer, forced Cenozoic and Mesozoic rocks of the Midwest westward, piling them up more than a mile high.
An article with the title, "The Spreading Ocean Floor," was published by Robert S. Dietz, Ph.D., oceanographer, in the Saturday Evening Post, October 21, 1961. [complete reference: Robert S. Dietz, "The Spreading Ocean Floor," Saturday Evening Post, 234 (21 October 1961): 34-35, 94-96. GL,III, ed.] It tells of deep sea drilling several thousand feet, preliminary to a six mile hole through the Earth's crust and into an underlying rock known as the mantle, one thousand eight hundred miles thick, which comprises the vast bulk of the Earth. This mantle, moving beneath two continents, has forced them apart.
Many species of Pennsylvanian Flora occur in Western Europe and North America. They are identical on the two continents; too much so to be explained by transportation of fructifications over the Atlantic Ocean by wind or wave. And the vast width of the Atlantic Ocean appeared to preclude any close association.
Now comes the explanation:
The mantle, moving slowly beneath the two continents, has forced them apart. The shore line of North and South America fits perfectly with the shore line of Western europe and Africa. The Atlantic Ocean lies in a vast rift which has been gradually widening since the Period of coal forming vegetation. [See the drawing below, right, for the present day - GL,III]
Dr. Dietz's published article tells much more of geological changes in the Earth. The above comments are limited to the explanation of why so many of our Pennsylvanian Flora specimens are identical with those of Western Europe.
The drawing below, left shows the beginning of separation between N (North America), G (Greenland), and E (Europe); also the separation between S (South America) and A (Africa). The separations are indicated by the heavy black lines.
In the drawings below, the upper one represents the geological formations in their original condition. The lower one shows their movements westward, impelled by the underlying mantle, which stripped the Midwest of all formations above the Paleozoic. During the Cenozoic Era, this impelling force resulted in eruptions which transformed level plains into mountain chains, three miles or more above present sea level. So there actually were reptiles and mammals in the Midwest throughout the Cenozoic and mesozoic Eras, and [which were] forced westward, as shown in the lower drawing. What is now a region of Great Lakes was once an area of seas, lagoons and land, occupied at first by marine and terrestrial reptiles, and finally by mammals, all traces of which were obliterated as previously explained.
[unsigned, but in the rather shaky handwriting of] George Langford, Sr.