Concerning a Geological Explanation of the Origin and Present Distribution of the New Jersey Pine Barren Vegetation

Abstract

The Pine Barrens of southern New Jersey have long been regarded by botanists as of high scientific interest; indeed, few other areas in North America have attracted such long-continued and widespread attention. In an attempt to account for the origin and present distribution of the pine barren vegetation Harshberger ('11, '16) and Taylor ('12, '15) developed a geological theory which seems to have been widely accepted. During the course of ecological work within the so-called Plains, which are included in the Pine Barrens, the writer had occasion to inquire into the geological history of the region. It was surprising to find that the geological facts as now understood are quite different from the ideas which formed the foundation of the geological explanation of the origin and occurrence of the Pine Barrens as developed by Harshberger and Taylor. The purpose of this paper primarily is to show that the Harshberger-Taylor theory was based upon geological hypotheses which are no longer tenable. First, however, it seems desirable to trace the development of the theory from its beginning. Hollick (1899, 1900) evidently was the first writer who attempted to correlate the occurrence of the New Jersey Pine Barrens with underlying geological formations. He was of the opinion that the Pine Barrens were coextensive with the area of Tertiary sands and gravels. However, the first accurate map of the Pine Barrens, drawn by Stone in 1911, clearly shows that the area of the barrens is not coextensive with the area of Tertiary sands and gravels as Hollick suggested. Indeed, Stone ('11) may have had Hollick's work in mind when he wrote, Some attempt has been made to correlate these areas or parts of them with underlying geological formations, but a more accurate knowledge of the distribution of their plants shows that such correlation is not possible. The surface soil has far more to do with the matter than the underlying geological formation. The western boundary of the Pine Barrens is often the eastern edge of the cretaceous formation, but in the southern part of the state it is not so, the cretaceous lying in some places fifteen or twenty miles west of the Pines. In the same way the very distinct coast strip with its West Jersey flora is geologically the same formation as the Pine Barrens. Harshberger ('11) expressed views similar to those of Hollick and stated that, The geologic formations to the south and southeast of a line drawn