Interactive virtual fieldtrip as a tool for remote education

Abstract. Geoscience courses, such as geology and geomorphology, require not only classroom lessons and laboratory exercises, but field trips as well. However, the COVID-19 restrictions did not allow the prosecution of most planned field trips, and an alternative needed to be developed. The use of virtual field trips is one such alternative. Through them, one can not only visit any area of interest, but prepare themselves for any actual educational or exploratory field trip as well. Even though they do not, and should not, substitute any physical visit of a site of interest, they have many advantages when combined with a "live" field work, in comparison to a field trip for which no preparation has been made. Through this research, we compare the advantages and disadvantages of both virtual and real educational field trips based on the opinions of our students. We thus performed a virtual navigation on the island of Naxos, Cyclades (Aegean Sea, Greece) for a series of virtual field trips, which took place during webinars in the framework of Erasmus+ CIVIS. The virtual fieldtrip was also presented to the third-year students of the Faculty of Geology & Geo-environment, National and Kapodistrian University of Athens, in the framework of the obligatory course of Geomorphology. Upon completion, all participating students were asked to fill in a questionnaire in order to evaluate the contribution of virtual field trips to their education regarding geomorphology and state their opinion as to whether they can supplement and/or substitute actual field trips. Most of them stated that virtual field trips can aid, but not substitute the actual field work. Most students mentioned that they would attend another virtual field trip in the future, both as an alternative to classroom lessons and as a means of preparation for an actual field trip, but not in order not to attend the actual one.


The coasts of Naxos island, especially since Late Pleistocene, are determined by eustatic sea-level changes, whereas vertical tectonic movements bear no significant impact (Sakellariou & Galanidou, 2016); however, there are indications of tectonic control for the late Holocene in the broader area (Desruelles et al., 2009;Lykousis, 2009;Evelpidou et al., 2014). Evelpidou et al. (2014, for example, have found several submerged tidal notches in the southeastern Cyclades, which were attributed to 100 former seismic events, which have taken place since 3300 BP (Evelpidou et al. 2014(Evelpidou et al. , 2018. It is worth mentioning that no evidence of tectonic uplift (such as uplifted terraces, notches or beachrocks) has been found. There are many submerged landforms and other indicators at Naxos, such as beachrocks found down to a depth of 6 m (Evelpidou et al., 2012;Karkani et al., 2017).
The lithology of Naxos consists of various lithological formations with different resistance in erosion. These differences, in combination with the action of the hydrographic network and tectonics, have determined the present morphology. Evelpidou (2001) has identified six lithological units, namely marbles-schists, the migmatite, the granodiorite, Neogene sediments, Quaternary sediments and colluvial-alluvial sediments. Marbles and schists cover the largest part of the island, namely the 120 central, northern, southern and eastern part, except for the migmatite dome in the center. Neogene, Quaternary and colluvialalluvial sediments are almost absent in this part of the island and, alongside the granodiorite, they are abundant on the west coasts of Naxos (Evelpidou, 2001).

Geomorphology
The relief of Naxos is mainly mountainous, especially its eastern, northern and southern part. It is characterized by a mountain 125 range with a direction N-S. Its highest summit, Zeus, is found in the center of the range and reaches 1,001 meters, which is also the highest point of the Cyclades. The western part of the island is, on the contrary, milder (Evelpidou, 2001). As already noted, the lithology of Naxos consists of various lithological formations with different resistance to erosion, which, in combination with the action of the hydrographic network and tectonics, has created the present morphology. Therefore, Naxos has many landforms and geomorphological features that result from differential erosion (Evelpidou, 2001). This geological 130 and tectonical setting has led to the formation of several landforms, associated with several environments (e.g. coastal, lagoonal, aeolian etc.) (Evelpidou, 2001). This is the main reason why this region was chosen as a study area and as a virtual field trip destination. It has the potential to aid students in recognizing various landforms, whereas it can offer them information about their formation processes. Additionally, several sites have an intriguing palaeogeographical evolution during the Quaternary, which can further aid students in understanding the principles of geomorphology. 135 Due to the variation of lithologies, the coasts of Naxos are also diverse. The western part, as mentioned before, is mainly dominated by alluvial sediments and granodiorite, hence the low morphology and the abundance of beaches. On the contrary, the rest of the island's coasts include other lithologies (marbles and schists) and are relatively steep and with very few beaches (Evelpidou, 2001).

Coastal wetlands and lagoons
Coastal wetlands and lagoons are particularly vulnerable to local palaeo-environmental changes and they constitute a powerful tool for tracking changes of the last thousand years in the coastal zone. Sea-level changes, climatic changes and human 170 interventions are recorded in the sediments of coastal swamps and wetlands, making these environments ideal for palaeogeographic reconstructions.
In Naxos island, many lagoons have been formed in the western coastal zone. Two characteristic examples highlight the evolution of the western coasts during the late Holocene, Agios Georgios and Mikri Vigla (Evelpidou et al. 2010;2012). At Agios Georgios, a series of coring revealed that the area was a lagoon 6000 years ago while today it is a wetland. This area 175 used to be a harbor, as it was an active lagoon from at least 6144 BP until 232 BP, and probably served Yria at that time (Evelpidou et al., 2012). Nowadays, a tombolo formation is visible in the area. Its development is owed to coastal currents that transported and deposited the sand between Manto island and the adjacent beach. The reef in front of Manto island consists of beachrocks that lie slightly lower than sea level, down to a depth of 1.9 m. The underwater beachrocks represent fossilized shorelines of 1500 years ago and 3400-4500 years ago (Karkani et al., 2017). Today these beachrocks protect the coast from 180 erosion due to wave action, and sea level rise. A few kilometers to the south, Vigla area is characterized by low land morphology crossed by torrents of temporary flow, coastal lagoons, dunes and sandy beaches (Fig. 4). Angular pieces of granodiorite and river-torrent depositions appear on the fringes of the alluvial plain. In the Vigla area, two beachrock benches, along with sand dunes represent the dominant coastal landforms. The analysis of sediments and micro-faunal content from Vigla corings revealed that during 3800 BP to 1625 BP 185 the area of Vigla was an active lagoon (Evelpidou et al., 2012). At least during the Bronze Age (3300 BC-1200 BC), Vigla may have been a place where boats could anchor. The beachrocks acted as a "barrier" subsiding periodically, allowing the entrance of sea water into the gulf. Vigla area was protected, like St. Georgios Bay, by a beachrock bench. At the onshore section, the hydrographic network 3000 years ago probably discharged in the Vigla bay, while today part of this network has migrated southeast (Evelpidou et al., 2012). 190

Tidal notches
Marine notches are horizontal U-shaped rock incisions along coastal cliffs. They are created through wave erosion, chemical weathering and/or bioerosion. Tidal notches are a special type of marine notches, which form through bioerosion by several 195 endolithic and epilithic organisms that reside near the mean sea-level and are mainly found on carbonate cliffs (e.g. Pirazzoli, One of the main purposes of this virtual "excursion" was to train our students on coastal evolution, palaeogeographic reconstructions, sea-level changes and geoarchaeology. Therefore, through this virtual navigation, we intended to show the students some of the main landforms of the island of Naxos and correlate them with the geological and geomorphological 260 setting of the contextual area of interest. Through the ArcGIS StoryMaps application, they had the ability to observe geological, geomorphological and relief maps, photos, satellite images etc., thus combining the optical factor with their previous geological knowledge and the lectures during the virtual field trip. An important aspect of StoryMaps is the availability of interactive