IN A FEW WORDS

Origins 15(2):47-48 (1988).

Brief summaries of the main conclusions of the leading presentations are given below for those who may find the complete articles too long or technical.

EXPANDING EARTH?

    Plate tectonics, which suggests that the crust of the earth is composed of a few plates fitted together like pieces of a puzzle, has been very successful in explaining surface features of the earth, such as mountains, ocean trenches, volcanos and earthquakes. However, some of the evidence to support it is ambiguous and the source of plate motion has not been unequivocally identified. Motivated by these problems, a few earth scientists have proposed an alternative model, the expanding earth. This article first considers satellite and interferometry measurements which were supposed to provide a definitive test of the two models. However, despite phenomenal accuracy, the error associated with these measurements is still too large to distinguish between the models. Additional evidence favoring the expanding earth is discussed, including the superior fit of the continents that it allows. This is followed by some of the problems that are associated with it, such as the source of expansion. Finally, some of the problems of plate tectonics are considered, most significant of which may be the mechanism that moves the plates.
    In summary, there are difficulties with both models. Currently, plate tectonics seems to be the more adequate of the two models, but that may reflect the time invested in it. Perhaps a more acceptable model would involve the synthesis of the two concepts. Unfortunately, it appears that such a combination would import the difficulties of finding suitable causes for both expansion and plate motion.

THOSE GAPS IN THE SEDIMENTARY LAYERS

    The layers of sedimentary rock that we see over the surface of the earth usually appear as parallel features that are often spread over wide areas. What does not appear to the casual observer is that between some of these layers major portions of the stratigraphic (geologic) column are missing. These gaps between the layers tell a story related to the age of these layers.
    Geologists can tell that a portion of the layers is missing because in other parts of the word layers with characteristic fossils are found between the layers represented at the gaps. For instance, near the bottom of the Grand Canyon, the Ordovician and Silurian portions of the geologic column are missing between some of the parallel layers present. The missing portion represents an assumed 100 million years of layers found elsewhere.
    The crucial question is: Is there evidence of that 100 million-year gap, or does it appear that the layers were laid down rapidly, as would be expected during the flood described in the book of Genesis? If there really is a 100 million-year gap, evidence of this in the form of erosion should be abundant. In fact, current rates of erosion are so rapid that erosion would completely eliminate layers below the gaps in the time span assumed.
    These gaps are common, and it appears that the erosion and other features expected during these long gaps in deposition are not there. This suggests that the layers were laid down rapidly. The absence of the expected evidence for long ages challenges the standard geologic time scale of thousands of millions of years for the formation of the strata of the earth.