Monument Future - Siegfried Siegesmund

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Heidelberg.

      Wang, Q., Ji, S., Sun, S., Marcotte, D., 2009. Correlations between compressional and shear wave velocities and corresponding Poisson’s ratios for some common rocks and sulfide ores. Tectonophysics 469, 61–72.

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       A STUDY ON NONDESTRUCTIVE DIAGNOSIS AND CONSERVATION SCHEME OF KOREAN DINOSAUR EGG FOSSIL SITES IN HWASEONG GOJEONGRI

      IN: SIEGESMUND, S. & MIDDENDORF, B. (EDS.): MONUMENT FUTURE: DECAY AND CONSERVATION OF STONE.

       – PROCEEDINGS OF THE 14TH INTERNATIONAL CONGRESS ON THE DETERIORATION AND CONSERVATION OF STONE –

       VOLUME I AND VOLUME II. MITTELDEUTSCHER VERLAG 2020.

      3 Conservation Science Division, National Research Institute of Cultural Heritage, Daejeon, 34122, Republic of Korea

       Abstract

      The Dinosaur Egg Fossil Site at Hwaseong Gojeongri in the Republic of Korea (which was discovered while investigating the ecological changes of the tidal mudflats that were revealed after the Sihwa Lake Seawall’s completion) is the first place in Korea where a large number of fossilized dinosaur eggs and egg nests have been found. In particular, it is Korea’s largest dinosaur egg fossil site. Additionally, because it is rare to find so many dinosaur egg fossils in one location, it was designated as the Korean Natural Monument No. 414, in recognition of its natural historic and academic value.

      After the last conservation treatment, which was carried out in 2008 because the fossilized dinosaur eggs had been exposed to the ground’s surface for nine years and had been damaged by artificial damage, natural weathering, and erosion from acid rain, the fossil site’s host rock was in urgent need of conservation. Therefore, this study investigated the material properties of rocks with dinosaur eggs, evaluated its weathering and damage, and conducted various non-destructive precision diagnoses.

      In addition, the exposure of fossil-bearing rock layers to the external environment accelerates damage through natural weathering due to physical, chemical, and biological factors. Therefore, in order to resist weathering, even if the fossil is directly exposed to outdoor, researching consolidation reagent and adhesives suitable for a fossil site is essential. This study carried out indoor and field application experiments on the same rock types and rocks that make up the fossil site to select the suitable consolidation reagent for actual conservation treatment. Furthermore, by evaluating suitability through field application experiments, they were used for conservation works.

      Keywords: Dinosaur egg fossil sites, Deterioration, Diagnosis, Conservation, Consolidants

       Introduction

      Sihwa Lake is located at the Gojeongri, Hwaseong site in the Republic of Korea. The place where dinosaur egg fossils were discovered is reclaimed land on the south side of Sihwa Lake, which appeared after the construction of the Sihwa Lake Seawall. Gojeongri is the first location in Asia where a group of dinosaur egg fossils was discovered. The Asian countries in which the highest number of dinosaur eggs have been found are China and Mongolia. In China, however, a place where a group of dinosaurs had lain eggs has not yet been found. Recently, 198the second group-spawning site in Asia was discovered in Mongolia. Therefore, the Gojeongri site holds significant academic value as a globally-rare, group-spawning site.

      The dinosaur egg fossils were found on twelve small islands that existed before the seawall was built. The fossil sites are distributed on the slopes and at the base of several small and large islands. Furthermore, there are now decks installed for visitors to look around the Mumyeongsom, Hahanyeom, Nudebawee, and Junghanyeom sites (Fig. 1).

      Figure 1: Distribution map showing the dinosaur egg fossil sites in Hwasung Gojeongri.

      The fossil sites, however, were submerged in seawater and are now located adjacent to industrial complexes and road networks, both of which emit toxic gases that cause acid rain that has a deadly effect on fossil conservation. As of today, 203 dinosaur egg fossils have been discovered at fifty-eight sites. Some basic research on the fossil sites has been conducted, according to which there are three types of dinosaur eggs: Faveoloothid, Dendroolithid, and Elongatoolith (Lee et al. 2000; Lee, 2003, Fig. 2). The type two dinosaur egg fossils, which were found only atthe Gaemesom site, have not been reported worldwide.

      The first type of eggs are subspherical in shape, with an estimated maximum length of 13.5 cm and a width of 11.5 cm. The pores are large (0.34~0.45 mm in diameter), and are round or oval in cross section. The pore system is similar to multicanaliculate of the faveoloolithid-type eggs (Zhao and Ding, 1976).

      The second type is smaller than the first type, and its pore system is similar to prolatocanaliculate of the dendroolithid-type eggs. The pore canals originate mainly in the interspaces between the shell units. These characteristics indicate that the dinosaur egg is a new dinosaur egg belonging to the dendrolithid-type (Lee, 2003).

      The third type of eggs is represented by several pieces of eggshells in one location. These eggshells are 1 mm thick and have a linearituberculate surface texture, which differs from the sagenotuberculate ornamentation of the first egg type. This type of dinosaur egg is likely to be of theropod, and classed as an elongatoolith-type (Zhao and Ding, 1976).

      On-site investigation revealed that the dinosaur egg fossils and the matrix rocks were damaged in several places. Because the fossils were exposed to rapid environmental changes and nature, various physical, chemical, and biological factors contributed to destroying the eggs’ original shapes. Therefore, it is necessary to investigate the fossil damage and to establish conservation measures in response to the rising attention toward accelerated damage of dinosaur egg fossils (Fig. 2).

      Figure 2: Representative types of the dinosaur egg fossils from Hwasung Gojeongri. (left) Type 1, (middle) Type 2 and (right) Type 3.

       199Materials and Methods

      This study conducted a non-destructive precise diagnosis to comprehensively examine the conservation status of the fossil sites, through which conservation schemes were established. To this end, the mineralogical characteristics of the fossil sites were analyzed, and a surface deterioration assessment and a test on the constituent rocks’ physical properties were carried out.

      Furthermore, the damage types were recorded at the site to identify the damage type, location, and distribution of rocks generated by locality at the fossil site. Based on these recordings, a damage map was drawn up and quantitative damage rates were estimated. For blistering, which is difficult to observe with the naked eye, the location and actual area were determined by using both infrared thermography and a percussion technique. The infrared thermal imaging camera used in the analysis was FLIR’s T640 model. Thermographic images were obtained through an active method of detecting the blistering that is caused by instantaneous temperature changes due to artificial heat; a near-infrared

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