Approximately two hundred million years ago, as continental Pangea was coming apart, extensive volcanic activity added sufficient quantities of ash to the atmosphere to alter the climate and cause mass extinctions. Could this episode be the source of common cobble-like fossil shapes?
Non-arbitrary rock shapes became the focus of this project ten years ago. Over time, recurring shapes became recognizable. Multiple examples were then collected. A prevailing characteristic was that most shapes could be categorized as misshapen. The form of a typical misshape can be illustrated by the sculptural difference between three dimensions and a bas relief.
With only a rock-like consistency to go on, context could be a key to finding a way of verifying that a rock is a kind of fossil. Context could take the form of a larger group, a mineral type or differences between members of a recurring type.
Color is a way to distinguish mineral types: green, raw umber, sienna, or dark gray or black. By gathering examples and comparing two mineral types found on Mount Desert Island, Maine, the correspondence although incomplete, is thus far, one to one. This would suggest that some shapes are as they appear. And if so, the next questions might be: Why are so many misshapen and What might that say about the process in which they formed?
As a process, it might be reasonable to assume that water played a role. A bas relief misshape has the appearance of having been a material like peanut butter that settled onto a surface. A possible deconstruction of the process, would include three basic ingredients. Minerals in solution were absorbed. Shapes were subjected to misshape, and the crystallization over time was homogenous. The process may have included a complex sequence or chemistry but whereas the number of examples is considerable, it would suggest that in whatever way the rocks crystallized, it wasn’t a rare or unusual occurrence.
One hypothesis that could account for misshapen forms and the homogeneity of a typical example, would involve a colloidal material. Insolubility and being colloidal are properties of a protein. Mineral solutions that crystallize as a rock, would assume the shape but lack the detail of a mineral replacement.
Another context in which evidence might be found is the way matching examples differ. This can be seen with multiple versions of a recognizable type. A drawing of the type used in this demonstration shows a distinct profile. The unusual feature of the first example is a textural, subsurface pattern, revealed in a fracture at one end. Another example of the same type is unusual in that an apparent surface layer is cracked. By cross-referencing examples like these, a composite picture emerges. Contrary to first impression, not all examples are strictly homogenous.
Shapes to which the protein hypothesis could apply, are the lump-like forms. In this case, misshapes are distinctive. When a dent is met by an opposing bulge, the form looks misshapen. Some of the dents include a superficial crack-like feature. Some of the indentations fit together as if caused by an adjacent example. Some misshapes are an elliptical form in bas-relief. From the same location, there are a few examples which appear to not have been misshapen.
In Maine, most often examples are abraded, or even polished to some extent. Some have characteristic gouges and scratches. The examples that are found in glacially deposited silt, suggest that the gouges are due to ice age scarring. In Maine the traditional view is that the ice age is responsible for a total transformation of the landscape. However some examples suggest that this may not apply to every rock.
In some cases, delicate examples may have come through the ice age unchanged. An indication of this can be found in the condition of other fossils such as a carbonized pattern on the surface of a misshapen form. This example was found along the shore at Western Bay on Mount Desert Island.
