The Need for Protecting, Promoting, and Managing a Quaternary Geoheritage Site: Bahluieț Valley at Costești Village (Moldavian Plateau, North-Eastern Romania)

The Bahluieț Valley at Costești village geosite has recently been studied and proposed as a geoheritage site. Previous investigations of the study area were focused on the Costești-Cier archaeological site, which is currently integrated into the National Archaeological Repertoire. In this archaeological site, different levels of populations have been studied (Eneolithic Cucuteni A, Cucuteni AB, and Horodiștea-Erbiceni Culture populations) as well as an earth wall from La Tene (8th‒10th/eleventh century BC) and a 15th‒seventeenth century AD necropolis. In the area of the present-day Costești village, Bahluieț River leaves the Suceava Plateau area (with altitudes of 350‒550 m a.s.l.) and enters the Jijia Hills (with altitudes of 50 to 200 m a.s.l.), flowing between Ulmiș Hill (306 m a.s.l., at north) and Ruginii Hill (326 m a.s.l., at the south). This valley, which is incised more than 100 m below the plateau level, suddenly becomes broader because of massive Late Pleistocene landslides that covered the former Bahluieț river floodplain and are now fossilized by fluvial deposits. During the Holocene, river incision detached paleochannels and fluvial terraces, while the landslides reactivated through retrogressive mechanisms, creating a complex landslide. A cut-off meander island hosts the Costești-Cier archaeological site, which is currently being actively eroded by the river. In the riverbank of this island, a multi-layered stratigraphy can be seen, consisting of landslide and fluvial deposits, palaeosols, and archaeological remains. The layered deposits, the complex landslide, and the fluvial processes have the potential to become one of the most representative Quaternary sites of the Moldavian Plateau and Romania. By using geomorphosite assessment, geomorphological mapping, optically stimulated luminescence dating, and concepts of geoconservation, I show (i) the importance of the geosite due to the presence of the oldest dated fossil landslide in Romania and to the landslide-fluvial-archaeological relations and (ii) the need for protection at local, regional, and national levels considering the active processes that affect the site. I propose a geoconservation strategy for management and promotion of the geoheritage site.


Introduction
Fluvial erosion and mass wasting are geomorphologic processes that control landform evolution (Korup and Schlunegger 2007;Larsen and Montgomery 2012) and create specific landforms: valleys, channels, and landslides. These processes can produce geomorphological hazards with adverse effects on human society (Monteleone and Sabatino 2014;Davies 2015).
The Moldavian Plateau is a lowland hilly area representative for Romania (Fig. 1), where landslides are a permanent phenomenon, coexisting and having feedbacks with river incision . In this area, landsliding occurred in the Late Pleistocene (Niculiță et al. 2016b; Niculiță 2020a, b) and Early Holocene (Niculiță et al. 2016a) and reactivated intensively during the Late Holocene and in recent times (Niculiță et al. 2016a, b;Niculiță 2020a, b). Many villages or cities developed on the landslide areas, so the destructive potential of landslides could negatively influence human society (Văculişteanu et al. 2019). Topography shaped by landslide processes, represented by hill plateaus bordered by steep escarpments tens of meters high, provided ancient populations with naturally defensive places to build their hillforts and fortified settlements ( Fig. 1: -locations of fortified sites in the Moldavian Plateau are shown). The archaeological topography has been used to assess the relative chronology of Moldavian Plateau landslides during the Holocene (Niculiță et al. 2016a. These locations are important heritage sites for Romanian prehistory, but landslides that developed after the population disappeared represent a significant risk factor for the archaeological sites (Niculiță and Mărgărint 2018). River and gully incision, which triggers but also follows landsliding, is physically destroying entire or parts of geoheritage and archaeological sites. The geomorphological, paleogeographical, and archaeological heritage has been used to argue for the geoheritage status (Niculiță and Mărgărint 2018) of ten such sites described first by Niculiță et al. (2016a). From the ten sites, two showed the potential to represent great importance for Moldavian Plateau geoheritage by having the biggest score in a geomorphosite evaluation (Niculiță and Mărgărint 2018): Băiceni Hillslope and Bahluieț Valley at Costești village. While the Băiceni Hillslope obtained the highest score, the Bahluieț Valley at Costești village appeared attractive because the landsliding and the archaeological topography are also related to fluvial terraces and fluvial processes, which generated exposure of layered deposits formed through interaction of the processes mentioned above. It was assessed that these layered deposits have potential to show the Pleniglacial to Holocene evolution of the contact area between the Suceava Plateau and Jijia Hills and are one of the most representative Quaternary sites of the Moldavian Plateau Niculiță and Mărgărint 2018;Niculiță 2020a, b).
Considering these aspects, it is of both scientific and practical interest to study the complex interactions between archaeological heritage sites, rivers, and landslides, with the implications for managing this important site. This study describes the geomorphological and archaeological context of the Bahluieț Valley at the Costești village geoheritage site (Fig. 2) and argues for its protection, promotion, and management through geoconservation.

Geological and Geomorphological Setting of the Bahluieț Valley at Costești
Costești village is located at the transition of the Bahluieț river from the Siret Plateau (Tufescu 1935(Tufescu , 1937a, a subdivision of the Suceava Plateau (east of Siret River) to Jijia Hills (Fig. 2). In this area, the Bahluieț river flows between Ulmiş hill (306 m a.s.l.) at the north and Crucii hill (235 m a.s.l.) with a north-west to a south-east direction (Fig. 3). The river is incised into monoclinal strata of the Carpathian foreland basin, with a north-west to southeast dip direction (de Leeuw et al. 2020), exposing Miocene strata as bands along the hillslopes. The Serravallian to Tortonian deposits (corresponding in the Dacian Basin to Volhynian to Bessarabian) are mud-rich siliciclastic offshore deposits formed in front of an axial fluvial-deltaic system, covered by shell-rich deposits of the prograding late Bessarabian shoreline (de Leeuw et al. 2020). The foreland basin was overfilled at 5.8 Ma. Still, exhumation in the north-western part is older (even 12 Ma), showing post-orogenetic uplift and a gentle south-east tilt, with several hundred meters of sediment being eroded (de Leeuw et al. 2020). The Pleistocene to Holocene evolution of the study area is not well dated. Still, the general framework was established with radiocarbon dating by Niculiță (2020a, b) Holocene (8-4 ka BP) filling of the valley with formation of a floodplain stable since 2-3 ka BP. In the last 2 ka BP, the present-day channels incised, and the floodplain aggraded through flood mud deposition (Niculiță 2020a, b). A landslide activity model consistent with this framework invokes the magnitude of the landslide events decreasing toward the present day with the activation moving from the slope base upslope through a retrogressive mechanism, generating compound and complex landslides covering entire hillslopes (Niculiță et al. 2016aNiculiță 2020a, b).
The geology of the study area was studied by Cobălcescu (1883), Tufescu (1935), Macarovici and Turculeț (1956), Ştefan (1989), and Ionesi et al. (2005). The correlation of Eastern Parathethys regional stratigraphy with the International Chronostratigraphic Chart  (Cohen et al. 2013) is established based on information from Pevzner and Vangengeim (1993), Jones and Simmons (1997), and Rögl (1998) and is shown in Fig. 4. The most detailed lithostratigraphic column was created by Ștefan (1989) and began with Late Volhynian rocks ( Fig. 4): the Oneaga Clays Formation and the overlapping Lespezi-Tudora Sands (Fig. 5b) and Sandstones Formation. The Oneaga Clays Formation (220 m thick) comprises compacted and stratified mudstones in the basal part, which has sand lenses or layers in the upper part, and appears tilted in some sectors (Ștefan 1989 -as is the case also in Fig. 5a). In the study area, these rocks outcrop only in the Bahluieț channel downstream of the landslide area. The Lespezi-Tudora Sands and Sandstones Formation is 35 m thick and is composed of intercalations of gray sand beds and quarzitic sandstones. The sands were also found bellow the floodplain downstream of the landslide area and are altered (Fig. 5b). The overlaying Early Bessarabian rocks suite starts with the Băiceni Clays and Sands Formation (40-100-m thickness), composed of basal mudstones and siltstones overlain by quarzitic sands. In the study area, the Băiceni Clays, there is a bluish-gray mudstone facies with thin sand intercalations found in a quarry on the left landslide hillslope (Fig. 5c). The Băiceni Sands Formation was found in a quarry (opened for the construction of the earth dams shown in Fig. 2), downstream of the study area, as siltstone with sand intercalations (Fig. 5d). The Hărmănești Oolitic Limestone (maximum thickness 4-5 m, composed of slates of oomicrite), covering the Băiceni Sands and Clays Formation, was found only as a fragment (insert on Fig. 5d) in the Băiceni Sands quarry. Over the oolitic limestone, there is a layer of quarzitic sands known as Bahlui-Sirețel Sands Formation, with 10-15-m thickness which has good outcrops in a gully downstream of the study area and upslope of the Băiceni Sands quarry (Fig. 5e). The second oolitic limestone level, named Hârlău Oolitic Limestone Formation, also has 4-5-m thickness, with oolitic limestones, microconglomerates, and sand layers (Fig. 5f). The Sticlăria-Sângeap Sands Formation with 35-40-m thickness composed of intercalations of sands and siltstones (Fig. 5g) is overlain by the Crivești Oolitic Sandstone (4-5 m thick) composed of quartz-arenites with oolitic limestone and sand layers (Fig. 5h), both identified in the study area. The Humosu Sands Formation has 100-m thickness with sands and layers of mudstones but is highly eroded in the study area, appearing as a thin layer on the plateaus. Ionesi et al. (2005) considered the whole Bessarabian column as a single formation called Dealu Mare. The geological formations were identified in the field (Fig. 5), mainly upstream and downstream of the studied area (because in the study area they are covered by landslide deposits): only the Crivești Oolitic Limestone Formation outcrops continuously in the Costești landslide scarps (Fig. 5g).
The widening of the valley before the river reaches the lower Jijia Hills area is due to multiple massive landslides (Niculiță et al. 2016a,b;Niculiță and Mărgărint 2018;Niculiță 2020a, b), which deposited material on the floodplain. The geological framework favored the landslides and the Bahluieț River incision (more than 125 m altitude amplitude). The age of the first generation of landslides (fossil landslides) was inferred to be at least Lateglacial from the stratigraphic relationship between the archaeological deposits, floodplain deposits, and the  (Niculiță et al. 2016a,b;Niculiță and Mărgărint 2018). Later, using radiocarbon data from the floodplain deposit Niculiță (2020a, b) confirmed the minimum Late Pleistocene (Pleniglacial) age. The fossil landslide bodies (due to the discontinuous outcropping, a single event cannot be proven) of maximum thickness estimated as 25 m (based on applying the sloping local base level approach of Jaboyedoff et al. 2004Jaboyedoff et al. , 2013, constrained by the ERT data from Niculiță et al. 2017) covered the former Bahluieț floodplain and were sealed with floodplain sediments between 2 to 7 m thick (based on field investigation of the Bahluieț river bank). In a later phase of fluvial evolution, the Bahluieţ River incised the landslide deposits and its own floodplain, as an in-grown meandering valley (cf. Davis 1906Davis , 1913Rick 1914;Dury 1964Dury 1965, creating cut-off fossil meanders (meander cores or spurs) and detaching several terrace levels (now at 5 to 15 m in relative height). The cut-off meanders separated two islands, one of which was used by the ancient population for a fortified settlement (Boghian et al. 2014b). Nowadays, the banks of the in-grown meander valley are continuously eroding due to the active channel's lateral migration, especially at the geoarchaeosite island ( Fig. 6). Further geomorphologic and geophysical investigations are needed to fully understand the topographic setting of the Cucutenian site on the island and the adjacent floodplain.
After the initial Upper Pleistocene failures, triggered by river incision, the landslides evolved retrogressively (Fig. 4) on the slopes on both sides of the valley. Thus, the landslide deposits on the floodplain and valley sides are multi-layered, as is the case in some areas in Europe (Margielewski 2006;Alexandrowicz and Margielewski 2010;Pánek et al. 2014). The initial landslides that generated the fossil landslide deposits were rotational rock slides with long runout. Coring and further geophysical investigations are needed to establish the timing and geometry of these deposits since the sources are both hillslopes, and they might cover a previous floodplain deposit. Nonetheless, the presence of tilted fossil landslide deposits was validated in the field across the Bahluieț river banks (Figs. 6 and 7). The fluvial sealing deposits, covered by retrogressive reactivated landslides ( Fig. 7) with rotational and translational mechanisms, were delineated using morphological approaches on high-resolution LiDAR DEMs (Niculiță et al. 2016a).

Costești Cier Archaeological Site Description
The Bahluieț Valley at Costești village site was only recently investigated from a geoheritage point of view and proposed as a geoheritage site (Niculiță and Mărgărint 2018) due to its geomorphologic, palaeogeographic, and archaeological values. The area is known in the scientific literature and was studied concerning the presence of the Costești-Cier archaeological site (Boghian 2009;Boghian et al. 2014a), recognized in the National Archaeological Repertoire (http:// ran. cimec. ro/ sel. asp? descr ipt= coste sti-coste sti-iasi-sitularheo logic-de-la-coste sti-cier-cod-sit-ran-95541. 01).
The archaeological site is located on a fluvial terrace and a meander island of the Bahluieț river, in the Costești Commune, Iași County (Figs. 1,2,4,6,7,8,and 9). The fluvial terrace site (Figs. 4 and 10) was heavily disturbed after 2000 by the construction of a local road, school, and soccer field. The meander island started eroding in the 1930 ): on the topographic army plans (http:// www. geospati al. org/ downl oad/ planu rile-direc toare-de-trage re? lang= en) and the Ciurea (1938) schema, the island has ~ 2500 m 2 (a hexagonal shape and general measures of 68 m N-S in length and 45 m W-E in width) and height of 25 m above the surrounding floodplain. Locals remarked on the presence of archaeological remains in the river bank (Ciurea 1938). For the 1939 situation, Matasă (1940) mentioned the existence of gullies on the hillslopes of the island (probably on the western bank).
The archaeological investigations showed that the site has different levels of populations (Table 1), being a pluristratified site, with archaeological deposits up to 2 m thick (Fig. 8). The oldest archaeological level is Cucuteni A, followed by Cucuteni AB. Over the Cucuteni layers, and intruding them, there are (i) a Horodiștea-Erbiceni Culture level with a necropolis, (ii) a medieval hut (8th-10th/eleventh century AD), and (iii) a 16th to seventeenth century AD necropolis with 35 burial tombs (Fig. 8). A Cucutenian defensive earth ditch was also found on the southern slope of the mound (Asăndulesei and Nicu, 2015). The geological formations identified in the field: (a) overturned Oneaga Clays outcropping in the Bahluieț channel, (b) Lespezi-Tudora Sands outcropping in the Bahluieț floodplain, (c) Băiceni clays outcropping on the left hillslope in a quarry, (d) Băiceni Sands outcropping in a quarry on the right hillslope, the inset showing a stone from the overlapping Hărmănești Oolitic Limestone, (e) Bahlui Sirețel Sands outcropping in a gully bank on the right hillslope, (f) Hârlău Oolitic Limestone outcropping in a landslide scarp on the right hillslope, (g) Sticlăria-Sângeap Sands outcropping in a road cut on the right hillslope, (h) Crivești Oolitic Limestone outcropping in a gully on the scarp of the Costești landslide ◂ From an archaeological point of view, the site is essential mainly for these archaeological findings ( Fig. 9): (i) anthropomorphic and zoomorphic representations ); (ii) painted ceramics, with kernos type of religious vase (Boghian, 2012); (iii) chipped and polished stone artifacts (Boghian et al. 2014c); (iv) artifacts made of clay and other materials (Boghian et al. 2014c;

Geomorphological Mapping
Geomorphological mapping performed in the field and on a high-resolution LiDAR DEM was used to establish a proper management plan. Three field surveys targeted identification of geology, of the channel and terraces, and of the landslides and gullies. Geomorphological mapping on the high-resolution data was made through automatic geomorphometric extraction of variables and features in SAGA GIS (Conrad et al. 2015) and manual digitization in Quantum GIS (QGIS. org 2021). The LiDAR point clouds (4-6 points per 1 m 2 ) acquired in 2012 were manually refined in order to obtain ground data, and through multilevel B-spline interpolation, two DEMs were obtained (see Niculiță et al. 2020 for details on the interpolation), one at 0.25 m spatial resolution for detailed manual mapping and one at 5 m spatial resolution for automatic geomorphometric mapping. The conceptual mapping system is based on the landforms that are considered important from the geoheritage point of view: landslides (delineated after Niculiță et al. 2016a andNiculiță 2020a, b, with guidelines using the Cruden and Varnes 1996 landslide elements), river channel, riverbanks, meander islands, fluvial terraces, and gullies. Generic catena-type units (Niculiță 2011) and fuzzy curvature-based classification (Schmidt and Hewitt 2004) implemented in SAGA GIS (Conrad et al. 2015) were used to frame the detailed mapping.
Based on the geomorphological characteristic of the study area, the following landforms types were mapped: (i) floodplains (extracted as the plain, channel, pit, and saddle classes of Schmidt and Hewitt (2004)) located at low altitudes and by thresholding catchment area; (ii) hillslopes, consisting of   (Boghian et al., 2014c(Boghian et al., , 2015Enea et al., 2016), (d) to (h) human representations on ceram-ics or as idols (Boghian et al., 2014c(Boghian et al., , 2015Enea et al., 2016), (i) and (j) bone tools (Boghian et al., 2014c), (k) flint tools (Boghian et al., 2014c) the hollows and spurs and foot, back and shoulder types of slope of Schmidt and Hewitt (2004); (iii) plateaux consisting of plain, channel, and saddle classes of Schmidt and Hewitt (2004) and located at high altitudes; (iv) ridges, consisting of ridge and peak classes of Schmidt and Hewitt (2004) and located at high altitudes; and (v) terraces, consisting of the saddle, channel, pit, and peak classes of Schmidt and Hewitt (2004) and located on the hillslopes around the Bahluieţ channel.

Absolute Dating of the Terrace Deposits
Because in the area of the geomorpho-archaeosite, the terrace deposits do not contain datable organic matter, the optically stimulated luminescence dating method was chosen to establish a chronology of the geomorphological evolution.
The samples were taken in custom-made sharpened steel tubes which were inserted in the sediment using a pounding cap. An aluminum foil plug was inserted at the sharpened end in order to fix the sample, avoiding sample mixing, and an aluminum end cap was used to seal the sample. Soil density drive tubes were used to sample material for gravimetric water estimation. The samples were dried in an oven at 110 °C for 24 h, and the percentage of water from the sample was derived through weighting before and after drying. The sample for the environmental dose rate was taken from a 20 cm range around the sample location.
Two samples were collected from the terrace deposit under the archaeological site, which outcrops in the river bank (Fig. 6c). The first sample was taken from a depth of 1 m under the paleosoil and 3 m from the surface. The second sample was taken from 1 m below the first.  Approximately 15 cm of exposed sediment was removed prior to the sampling. The optically stimulated luminescence dating was performed by György Sipos from the OSL laboratory of Szeged University. The laboratory is equipped with a RISO TL/ OSL DA-15 luminescence reader fitted with a calibrated 90Sr/90Y source. Stimulation of the grains was carried out using a blue (470 nm) and IR (870 nm) light-emitting diodes (LED), and the detection was done through a U-340 filter. Different types of the Single Aliquot Regeneration (SAR) protocol was used Wintle 2000, 2003;Wintle and Murray 2006;Thiel et al. 2011;Buylaert et al. 2012) for measurements. Before the measurement of the equivalent dose (De), tests were carried out to determine optimal temperature parameters and the reproducibility of the SAR procedure (combined preheat and dose recovery test). The equivalent dose was determined on several aliquots for of each sample. Only those aliquots were considered for De calculation which passed the following rejection criteria:(i) recycling ratio of 1.00 ± 0.10, (ii) maximum dose error of 10%, (iii) maximum recuperation of 5%, and (iv) maximum IR/OSL depletion ratio of 5%.
The sample De was determined based on each accepted aliquot De, using different statistical techniques (Galbraith et al. 1999). A decision was made based on overdispersion, skewness, and kurtosis values. Environmental dose rate D* was determined on the samples using a high-resolution, extended range gamma spectrometer (Canberra XtRa Coaxial HpGe detector). Dry dose rates were calculated using the conversion factors of Liritzis et al. (2013), while wet dose rates were assessed based on in situ water contents. The dose rate provided by cosmic radiation was determined based on the geographical position and depth of the samples below ground level, using the equation of Prescott and Hutton (1994).

Geomorphosite Evaluation
Considering that the present study improved the knowledge about the geomorphosite, the methodology applied by Niculiță and Mărgărint (2018) was used to recompute the values reported in Niculiță and Mărgărint (2018). The recomputed values are intensively discussed further in Sect. 4.2.

Geomorphological Evolution of the Geoheritage Site
Evaluationof the Bahluieț Valley at Costești geoheritage site by Niculiță and Mărgărint (2018) inferred a Late Pleistocene age for the fossil landslide; this age was confirmed by Niculiță (2020a, b). In the LAHAMP project (Niculiță 2020a, b), radiocarbon dating for several landslide sites in Moldavian Plateau was performed. While most of the landslide sites were dated to Holocene, organic matter from the terrace deposits that cover the Costești fossil landslide returned a date of 45, 920-43, 985 cal BP (Beta Analytics ID 518,575). This result implies that the fossil landslide was triggered in or before MIS3. Fieldwork along the Bahluieț channel network identified fossil landslide deposits under terrace deposits in another four places (Fig. 7) beside those at the geoarchaeosite. Due to the lack of other dateable organic material, in the section of the geoarchaeosite, two samples from the terrace deposits were dated with OSL. The results (Tables 2 and 3) show the late Pleniglacial age of the 3.5-4-m-thick floodplain deposits that sit over the landslide deposits. In this context, it is clear that the fossil landslide deposits correspond to different events and that the floodplain deposition of the terrace also varied in thickness and rate.
At the current geomorphologic research stage, the Late Pleistocene age of the fossil landslide is well constrained, without the possibility of specifying the precise timing of the triggering, but only upper bounds. These bounds imply that multiple events generated the landslide deposit. Through geophysical investigation and deep coring, future research might be able to show the age of the landslide events directly from landslide deposit dating or by constraining the age by dating possible floodplain deposits fossilized by the landslides. The geomorphological mapping suggests continuity of the retrogressive landslide reactivations that generated a complex landslide, during the evolution of the hillslopes. This landslide occupies the Bahluieț Valley, with fossil material from both hillslopes, fluvial cover, and Lateglacial and Holocene reactivations. The topography of the terrace deposits is not smooth, showing the presence of paleochannels and meander islands, the current incised channel being post-medieval.

Geomorphosite Evaluation
The new data on geomorphological evolution of the study area improves the geomorphosite assessment of Niculiță and Mărgărint (2018), making this geosite the most important in the Moldavian Plateau (  Table 2), the erosional and depositional features of both old and present-day processes are clearly defined. Regarding rareness (3.5 in Table 2), the fluvially incised fossil landslide is the only known occurrence in Romania. The diversity of elements (3.9 in Table 2) is increased, with three other elements being present besides the two evaluated in 2018: pre-LGM fossil landslides, Early Holocene relict landslides, Late Holocene old landslides, meander islands, and terraces.
In relation to additional value (ADIT in Table 2), the protected site value has increased since taking into account the full extent of the landslides. The geosite is under 5 km from Sârca-Podu Iloaiei reservoirs special area of conservation (SAC) for avifauna.
The aesthetic value (AEST in Table 2) changes considering the landslide complex. The observation conditions (5.1 from Table 2) increase due to numerous belvedere points and the absence of view restrictions from the geomorpho-archaeosite and the hillslopes.
Regarding the economic value (ECON in Table 2), accessibility (7.1 in Table 2) is raised due to access in the geoheritage site directly from the DN8A road and access to the geomorphoarchaeosite on paved roads.
Regarding the synthesis value (SYNTH in Table 2), the subcriterion fragility (8.4 in Table 2) is improved since the geoheritage site is very large and will suffer damage only from construction or mining activities which are also improbable.

Proposals for the Geoconservation Strategy
The current state of scientific knowledge supports an argument for geoconservation of the geoheritage site. In this sense, a geoconservation strategy based on scientific research, community involvement, and educational outreach is proposed. The strategy is as follows: (i) the geoheritage site needs to be recognized under a legal framework to make authorities aware of the protection needs; (ii) conservation agencies and groups need to be outreached to establish specific conservation approach plans; (iii) scientific study needs to be extended and used in auditing of the site; (iv) conservation proposals need to be formalized in a plan (Fig. 10); (v) after the plan is materialized, touristic management needs to be implemented; and (vi) future opportunities need to be assessed.

Rationale for Protecting and Managing Geoheritage Sites
Protected areas are key elements of the conservation of ecosystems, although these tools were contested (Woodley 1997). While this role cannot always be attributed to geoheritage sites, their protection and conservation are required, at least from a scientific point of view. Geoheritage sites are natural sites that have an outstanding value from a geological and geomorphological point of view. Regarding global approaches of nature conservation, geoheritage sites have various spatial scales. They can be inside or harbor unique ecosystems that need to be protected, in which case their conservation need and their intrinsic value are added to the biological parts. In other situations, while geosites harbor ecosystems, that may not necessarily be unique, the association creates unique landscapes, very often impacted by humans, which also require conservation from biological, natural, and cultural points of view (Phillips 1997). According to the IUCN classification of protected areas, geoheritage sites can be assigned to world heritage sites or geoparks (Dingwall et al. 2005). National designation is usually based on the geological/ geomorphological value, but sites are often included in wider protected areas (Dingwall et al. 2005). The equivalence between IUCN categories and Romanian protected areas categories is shown in Fig. 11.
The protection of geoheritage sites is thus important for maintaining geodiversity and biodiversity, which is good in general but crucial for some poor areas (Brockington and Wilkie 2015). The material benefits for local society are related to the funding and activities that can be attracted (Mansourian et al. 2008).
Considering the geoarchaeological and geomorphological context of the Costeşti Cier archaeological site and its surroundings, Niculiță and Mărgărint (2018) argued that the area could be considered a geoarchaeosite and a geosite. Besides this formal status and the protection of the archaeological site, clear measures should be taken to achieve national protection status. We propose inclusion first as a county-level protected area and later as a natural monument (Fig. 11). Further on, threats due to the continuous erosion of the Bahluieț river must be addressed to protect the site and assure its management. This is an immediate need (Mac-Donald 1990) since the erosion is active, and the riverbank is receding actively (Fig. 12). To respond to this threat, salvage excavations of the archaeological site should continue, and measures of bank stabilization are needed to prevent further loss of the site..

Conservation of the Costești Geoheritage Site: State or Community-Based?
State-managed conservation can benefit from better funding, management and regulation. At the same time, any failure to provide both funding and good management Table 3 The results of the reevaluation of the geomorphosite indirect evaluation (Niculiță and Mărgărint 2018) The codes from the headers, refers to the indirect evaluation methodology proposed by Mărgărint 2018, VV Viștea Valley site (Comănescu andNedelea 2017), T total (in bold), GT global total, S6 Băiceni site (Niculiță and Mărgărint 2018), S7 Costești site (Niculiță and Mărgărint 2018) . 11 The topographic situation of the geomorpho-archaeosite and the bank retreat of the meander island Fig. 12 Equivalence between the IUCN and Romanian protected area categories (adapted after Appleton 2010) might require local community involvement. While the later would be beneficial, especially if geoheritage tourism can provide profit for the local community in rural areas (Bandyopadhyay et al. 2009;Lapeyre 2010), there are frequent cases when it fails (van der Straaten 1997;Emerton 2001), especially if the local communities are not technically and theoretically well prepared (Blangy 1997). Assigning a cultural value to a geoheritage site could benefit its protection as happens for wildlife value (Infield 2011), both in state and local community-managed conservation. Especially if the value added by geoheritage sites is related to geoscience and environmental education, this could improve support by local communities (Biderman and Bosak 1997). Also, when the geoheritage areas are small, overlain by human communities, and owned by local landlords or communities, local stewardship initiatives could prove to work (Brown and Mitchell 1997), but not necessarily (Varangu 1997).
In the case of Costești geoheritage site, given the recent scientific interest, there is currently no protection for the archaeological site. According to Romanian law (Ordnance 43 from 2000, 258 Law from 2006), archaeological sites are protected by the local and the county administrations. The protected area is defined either as a surface where remains were found, as a buffer around that, or as the entire surface where geomorphological processes expose the archaeological deposit. Currently, there is no unified geodatabase showing the extent of these protected areas as is the case for natural protected areas, but only an inventory with a spatial component (in the best case, a point placed on the geographical position of the site) and an estimate of the site area (given in hectares). For Costești Cier archaeological site, which is contained in the Costești geoheritage site, the archaeological area is continuously shrinking (Fig. 12). The archaeological investigations are mainly for salvage, since the relict of meander island is eroding and anthropic interventions destroyed the fluvial terrace site ).
At the current state of the site's legal protection status, funds can be attracted by the local authorities or by the Prut-Bârlad Water Administration to protect the river bank. Funding for establishing a signage network, promotion, further studies, and specific facilities for geosite management can be attracted either by the local action groups (http:// galia sisud vest. ro/) or by the county administration. The funding required for protection, management, and conservation could be easier to obtain if the site became protected officially, at the county level as a first step. The management should be local, with supervision from the county level. The involvement of voluntary bodies should also be encouraged (Burek 2008).

Land Zoning and Land Use Planning of Protected Areas
The problem of regulating the use of land in protected areas is still unresolved. There are actually no indisputable proofs about how a certain land use/zoning decision will influence the protected area (Nelson et al. 1997). Especially where tourism and economic activities are involved, a trade-off will be required. The boundary of where these activities can harm or not the integrity of the protected area cannot be well defined (Blangy 1997;Varangu 1997).
Defining the extent of the protected area and the degree of human activity needs a careful investigation since the area is inhabited: imposing strict restrictions can have unwanted results, especially in rural and poor areas (Brockington and Wilkie 2015). A first step should be studying the possibility of including the area in the existing system of protected areas (Kattan 2006). The closest protected area near the Costeşti area is some 5 km toward the northeast, the Sârca-Podu Iloaiei reservoirs SAC for avifauna. A connection with this protected area would be hard to create due to the topography and land use. There could, however, be a possible future linkage through forested areas to the Dealul Mare -Hârlău Site of Communitary Importance (~ 20 km to the north).
In Fig. 10, we propose the extent of two separate areas: (i) the area of the geoarchaeosite, around the present-day meander island, which can easily be protected and managed since its area is a local public space, and (ii) the area of the geosite, which should include the site of Costeşti village. For the second area, we cannot yet propose specific measures until a further impact study on the local development potential is performed in order to estimate the impact of any protection measures. At least, specific hydro-technical measures should be implemented in the geoarchaeosite space in order to stop the bank erosion: this is the easiest and most direct path to follow for protection of the geosite. These hydro-technical works need to be performed in such a way that the local landscape integrity is kept.

Conclusions
Costești archaeosite is an exemplary site of Quaternary deposits and palaeogeographic evolution, unique in the Moldavian Plateau and in Romania, which requires geoconservation based on these values (Kiden et al. 1991). This status requires monitoring and management from the local, county, and national stakeholders, and plus specific geoconservation measures. Bahluieț Valley at Costești village is a geoheritage site containing an archaeosite and both an active and a passive geomorphosite, with an "educational exemplarity" since multiple geomorphological processes can be reconstructed at various spatial and temporal scales (Pelfini and Bolatti 2014). Besides the fossil landslide, which is unique in Romania, the geoheritage site is a complex landslide that can be used to show the reactivation patterns of mass movement processes through retrogressive evolution at the entire hillslope level (Chorobak and Cebulski 2014). The fluvial incision and deposition are very well exemplified, by both morphology and stratigraphy. We propose to use the site as a case study for hillslope and fluvial geomorphology courses at the bachelor's degree level. Furthermore, wider local publicity will raise awareness of the geomorphological processes which should be considered when changes in land use are proposed for landslide-prone slopes or areas threatened by river erosion.
The site's value is given by the presence of Quaternary landslides, Quaternary deposits, Quaternary fluvial geomorphology, and archaeological heritage. Despite its archaeologic status and geoheritage value, the site is not included in a protected area or in a touristic network. Given the accessibility of the location from the national road between Iași and Pașcani, if proper arrangement and signage are performed, the site can be included in the local and national geotouristic network (Newsome and Dowling 2006;Chen et al. 2015). Because of this new extended status, the geoheritage site needs to be protected through multidisciplinary management, by understanding the relevant natural processes (Sharpless 2002) and the anthropic modifications to be able to: (i) understand how the natural processes respond to anthropic (Niculiţă 2020b) and climate change disturbance (Niculiţă 2020a); (ii) determine the thresholds of natural and anthropic disturbances beyond which unacceptable acceleration of natural rates and magnitudes of change will occur (Niculiţă and Mărgărint 2018), and (iii) identify management options and measures which can be used to keep the disturbances below acceptable thresholds (Niculiţă 2018).
Nowadays, the river is eroding the mound, and immediate protection measures are needed to limit the destruction of such an important deposit and morphology. At the same time, a management plan is needed to promote the site at local, regional, and national levels. Further scientific investigations are required and can increase its value.