Reconsideration of the Natural Monument Geummubong Petrified Tree Fern Fossil Site, Ghilgok, Korea

Abstract

Chilgok Geummubong tree fern fossil site is the type locality where tree fern stem fossils (Cyathocaulis naktongensis) were first discovered by Tateiwa in 1925. Recognized for its academic value, it was designated as a natural monument in the 1930s during the Japanese colonial period, and preserved and managed for over 90 years. However, at the time of discovery, the stratigraphic level of tree fern fossils could not be located because the fossils were fragments detached from the rock body, and thus the Geummubong area where the conglomerate/sandstone layers of the Nakdong Formation are distributed, has been designated as a cultural heritage area. Only in the 2000s, when tree fern fossils were directly recovered from the outcrops near the designated area, the sedimentary rock facies containing the fossils were interpreted, and the anatomical characteristics of the Mesozoic tree fern fossils could be described and identified as a species level. Such studies are, in these days, redefining classification criteria done by Japanese paleontologist, Ogura. That is, Korean researchers pointed out that the classification criteria of the tree fern fossils (Cyathocaulis) reported early from Chilgok were ambiguous, and the possibility that the two species were the same species was suggested. In addition, it is necessary to reorganize designated areas as a way to resolve social conflicts and civil complaints caused by various regulations that have continued for a long time.