Geological Heritage As a New Kind of Natural Resource in the Siwa Oasis

Journal of African Earth Sciences 144 (2018) 151e160

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Journal of African Earth Sciences

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Geological heritage as a new kind of natural resource in the Siwa Oasis, Egypt: The ﬁrst assessment, comparison to the Russian South, and sustainable development issues

Emad S. Sallam a, Ahmed K. Abd El-Aal b, c, Yury A. Fedorov d, Olessia R. Bobrysheva e, * Dmitry A. Ruban e, a Department of Geology, Faculty of Science, Benha University, Farid Nada Street 15, Benha, 13518, Egypt b Civil Engineering Department, Faculty of Engineering, Najran University, King Abdulaziz Road, P.O Box 1988, Najran, 1988, Saudi Arabia c Department of Geology, Faculty of Science, Al-Azhar University, Assuit Branch, Assuit, 71524, Egypt d Department of Physical Geography, Ecology, and Nature Protection, Institute of Earth Sciences, Southern Federal University, Zorge Street 40, Rostov-on- Don, 344090, Russia e Department of Business in Hospitality Sphere, Higher School of Business, Southern Federal University, 23-ja linija Street 43, Rostov-on-Don, 344019, Russia article info abstract

Article history: Discovering new natural resources is important for sustainable development of remote oases in arid Received 31 January 2018 regions of Africa and the Middle East. The first comprehensive assessment of geological heritage of the Received in revised form Siwa Oasis in the northwestern part of Egypt is based on field inventory of potentially unique geological 8 April 2018 features and analysis of literature data. Comparison to similar features in the other parts of Egypt and the Accepted 11 April 2018 world, including the Russian South, is essential to evaluate the uniqueness of the described geological Available online 13 April 2018 phenomena. A total of nine geological heritage types are established in the Siwa Oasis. These include stratigraphical, palaeontological, sedimentary, palaeogeographical, hydrological and hydrogeological, Keywords: Geological conservation geothermal, pedological, geomorphological, and economical types. The most high-ranked are features Facies constituting sedimentary, palaeogeographical, and hydrological and hydrogeological types. The former Saline lakes can be found in the old Shali town built from evaporite stones experienced diagenetic changes, and the Therapeutic muds latter is local manifestation of the EoceneeOligocene palaeoenvironmental transition different from the Tourism global cooling trend. Additionally, saline lakes and pools, as well as stratigraphical sections, landforms, Russian South and some other features demonstrate certain uniqueness. A series of geosites are identified in the oasis Western desert and vicinities. Taken together, the geological heritage of the Siwa Oasis is significant for conservation and exploitation for research, education, and tourism purposes. It is suggested that geological tourism there should be combined with archaeological, industrial, and "ordinary" to become efficient and to contribute to the local sustainable development. Examples from the Russian South (the Big Tambukan and Big Yashalta lakes) permit to realize that the consideration of salt and therapeutic mud resource indicates on the higher value of the discussed geological heritage features of the Siwa Oasis. Moreover, this resource, which is of big uniqueness itself, can contribute substantially to tourism development on the basis of unique geological phenomena. © 2018 Elsevier Ltd. All rights reserved.

1. Introduction 2011; Wimbledon and Smith-Meyer, 2012; Gray, 2013; Henriques and Brilha, 2017; Reynard and Brilha, 2017). This term specifies A term geological heritage has been used widely in three past separate kind of natural resource (Gray, 2011, 2012; Prosser, 2013; decades to define geological features valuable to the society Ruban, 2017) that can (and should) be explored and then exploi- because of their uniqueness (Prosser et al., 2006; Henriques et al., ted sustainably in all countries. On the one hand, geological heritage is a part of natural heritage that deserves conservation because it bears important information about unique geological phenomena. On the other hand, geological heritage can be used for the * Corresponding author. purposes of geological education and tourism, i.e., for social and E-mail addresses: [email protected] (E.S. Sallam), [email protected] economic benefits. (D.A. Ruban). https://doi.org/10.1016/j.jafrearsci.2018.04.008 1464-343X/© 2018 Elsevier Ltd. All rights reserved. 152 E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160

Unfortunately, our present knowledge of geological heritage is part of the oasis lies below sea level with the lowest point of 18 m. strongly tied to Europe and South East Asia, and it is incomplete in The Siwa Depression is bounded by the Qattara Depression from the case of Africa. Egypt is not exclusion, although previous studies the east, the Jaghbub Depression from the west, the Great Sand Sea of El-Asmar et al. (2012), AbdelMaksoud and Hussien (2016), from the south, and the El-Diffa Plateau from the north. In the oasis, Plyusnina et al. (2016), Sallam and Ruban (2017), AbdelMaksoud there are many isolated hills forming buttes and mesas, including et al. (2018), and Sallam et al. (2018a, b) revealed its outstanding Gebel Siwa, Gebel El-Kosha, Qaret Khamsia, Gebel El-Dakror, etc. richness in unique geological features. Particularly, it has been (Fig. 2). The Siwa Oasis is covered by a variety of aeolian sands and found that many unique and spectacular geological phenomena sabkhas. The distinctive natural elements of the Siwa Oasis are concentrate in desert oases. Important stratigraphical sections, saline lakes (Table 1), which receive water from natural springs and palaeontological localities, well-preserved palaeogeographical from agricultural drainage. features, peculiar landforms, etc. can be found there. Moreover, the The Siwa Oasis has a complex geological setting (Fig. 1c). It is very occurrence in oasis facilitates conservation of this geological located within unstable tectonic belt in northern Egypt (Said, 1990). heritage, as well as its utility for education and tourism. This is a structurally controlled sedimentary basin (Issawi et al., The present study focuses on the geological heritage of the large 2009). The exposed sedimentary succession in the Siwa Depres- and historically well known Siwa Oasis in the northwest of Egypt sion ranges in age from the Middle Eocene to the Quaternary (Said, (Fig. 1a). The field investigations and the bibliographical survey 1962; Rabeh, 2012; Abdel-Fattah et al., 2013; Osman and Orabi, permit undertaking the first comprehensive assessment of this 2017)(Fig. 3). precious natural resource. The urgency of this study is dictated as The Eocene rocks crop out in small depressions, namely El-Qara by necessity of better understanding of the geological heritage of and El-Arag in the north- and southeastern parts of the Siwa Oasis, Egypt and entire Africa, as by importance of finding new, geology- respectively (Fig. 1c). These rocks are represented by the Mokattam related resources for sustainable development of remote oases in Formation (Lutetian) at the base and the Upper Hamra Formation arid regions. Moreover, the specific geological heritage features (Priabonian) above (Fig. 3). These formations are mainly composed available in the Siwa Oasis have to be compared with similar fea- of foraminiferal siliciclastic-carbonate rocks deposited in shallow- tures available in the other parts of the world. Particularly, lakes of marine reefal environments (Osman and Orabi, 2017). The Oligo- the semi-arid to arid zone of the Russian South are suitable for this cene rocks in the Siwa Oasis are represented by marine facies (El- purpose. Qara Formation) in the north and fluvio-marine facies (Qatrani Formation) in the south (Osman and Orabi, 2017). The El-Qara Formation consists mainly of grey, small-scale tabular cross- 2. Geological setting bedded foraminiferal limestones. The Qatrani Formation is represented by green glauconitic shales and calcareous sandstones 0 0 The Siwa Oasis (centered at 29 12 N and 25 53 E) is a natural containing shell fragments and silicified wood. depression located in the northwest of the Western Desert of Egypt, The Miocene rocks are widely exposed in the northern part of near the EgypteLibya border (Fig. 1a and b). Its area is ~1730 km2.A

Fig. 1. Geographical location (a), geosites (b), and geological setting (c) of the Siwa Oasis and the adjacent areas (geological map is based on CONOCO and EGPC, 1988). Labels AeG on b mark some geosites mentioned in this paper. E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160 153

limestones. It was accumulated in a shallow-marine environment (Abdel-Fattah et al., 2013). It yields rich Middle Miocene macro- and microfauna. The Marmarica Formation is subdivided into three members, namely the Oasis Member at the base, the Siwa Escarp- ment Member in the midst, and the El-Diffa Plateau Member at the top (Gindy and El-Askary, 1969; Said, 1990; Jones et al., 2006; Abdel-Fattah et al., 2013). The Pliocene sediments are not recorded in the Siwa Oasis. The Quaternary sediments are represented there by sabkha, salts, sand dunes, and sand and gravel sheets, which cover the southern and western parts of the oasis (Fig. 1c).

3. Methodology

The available approaches of geological heritage assessment differ (e.g., Ruban, 2010; Ellis, 2011; Fassoulas et al., 2012; Haag and Henriques, 2014; Sanso et al., 2015; Kubalikova and Kirchner, 2016; Reynard and Brilha, 2017). For the purposes of this study, the approach similar to that used in the previous works about geological heritage of Egypt (Plyusnina et al., 2016; Sallam et al., 2018a; b) is applied. The approach is as follows. First, the key geological features known from the literature and the previous field experience in the Siwa Oasis are visited for inventory, i.e., for formal examination and description. Second, the available literature sources are checked for finding the other evidence related to the potential geological heritage (bibliographical survey). Third, the collected information is used for establishment of unique geological features in the Siwa Oasis. The uniqueness is evaluated via comparison with other similar features known in Egypt and other countries. The features are attributed to geological heritage types (classification of these types proposed by Ruban (2010) is employed for this purpose; a total of 21 types are distinguished). Fourth, the rank of each geological heritage type is established. The ranks may be local (oasis-level), regional (province-level), national (country-level), and global (world-level) depending on the spatial uniqueness of Fig. 2. General views of the Siwa Oasis: a e Gebel El-Mawta and Siwa Lake, b e close- geological features (cf. Ruban, 2010). Fifth, geological heritage sites up view of Gebel El-Dakror. (geosites) representing the above-mentioned geological heritage types are identified. Each of them exhibit really unique information Table 1 about particular geological phenomena. The main lakes of the Siwa Oasis and the adjacent areas. Taken together, the results of such an analysis indicate on how precious is the geological heritage of the Siwa Oasis as a natural Name Location Approximate area, m2 Water TDS, ppm resource. This evidence forms foundation for further discussion of 0 00 El-Maraqi 29 14 00 N 27900 fresh/salt 101952 the possible conservation and exploitation of this resource (e.g., in 25 190 0000 E Zeitoun 29 090 0000 N 210940 salt 86400 the form of geological tourism) for the purposes of local socio- 25 470 0500 E economical development. Siwa 29 120 0000 N 32760 salt 118592 0 00 25 27 00 E 4. Results Temrah 29 110 5000 N 78700 salt 40512 25 420 3100 E Qureishit 29 110 0000 N 30536 salt 30512 Unique geological features established in the Siwa Oasis are 25 430 0000 E attributed to 9 geological heritage types, namely stratigraphical, palaeontological, sedimentary, palaeogeographical, hydrological and hydrogeological, geothermal, pedological, geomorphological, the Siwa Oasis (Fig. 1c). These rocks build the main bulk of the El- and economical types. These features and the relevant types differ Diffa Plateau. Deposition of the Miocene rocks in the Siwa by their uniqueness, and they are represented by a series of geosites Depression was controlled by shoreline shifts of a palaeosea (Fig. 1b, Table 2). Although all these types are essentially geological, (Abdel-Fattah et al., 2013). The Miocene rocks are subdivided into it is sensible to subdivide these provisionally into two groups two main rock packages, namely the Moghra Formation (Early depending on major features, namely "pure" geological features and Miocene) at the base and the Marmarica Formation (Middle geology-related environmental features. Descriptions of all types are Miocene) at the top (Fig. 3). The Moghra Formation consists of given below together with interpretation of their uniqueness. shallow-marine siliciclastic rocks with minor limestone in- tercalations. This formation is characterized by diverse assemblages 4.1. "Pure" geological features of micro- and macrofossils. The Marmarica Formation is composed of interbedded shales and fossiliferous marlstones at the base The stratigraphical geological heritage type is represented in the graded upward into snow-white, fossiliferous, coralline chalky Siwa Oasis by the lengthy section of the Marmarica Formation 154 E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160

Fig. 3. Composite stratigraphical section of the Siwa Oasis and the adjacent areas (after Abdel-Fattah et al., 2013; Osman and Orabi, 2017).

Table 2 Principal geoheritage characteristics of the Siwa Oasis and the adjacent areas.

Type Rank Representative geositesa, b

Stratigraphical Local Marmarica Formation section (A) Palaeontological Local exposed fossil whale skeleton (B) Sedimentary Global sand dunes (C), kershief constructions Palaeogeographical National sabkha deposits (D), Hydrological and hydrogeological National Sitra Lake (E), see other lakes in Table 1 Geothermal Local yet be to chosen Pedological Local yet be to chosen Geomorphological Local mushroom rock in the El-Qara Oasis (F) Economical Local salt extraction at El-Mallahat (G)

a Location of geosites marked as AeG is shown on Fig. 1a. b There are some other geosites in addition to those listed e see text for more details.

(Fig. 1a), which permits documentation of this sedimentary pack- frequent occurrence of macro- and microinvertebrates, silicified age and tracing its internal contacts with precision (Fig. 4a and b). wood, and other fossil remains in the PaleogeneeNeogene strata This mid-Miocene carbonate formation (Gindy and El-Askary, 1969; (Fig. 3). But the most unique are vertebrate finds like the exposed Said, 1990; Jones et al., 2006; Abdel-Fattah et al., 2013) outcrops fossil whale skeleton encountered to the east of the Siwa Oasis widely in the northwestern part of Egypt (Fig. 1c), and, thus, the (Figs. 1a and 5). The uniqueness is determined in this case by rarity uniqueness of the noted section is restricted to the territory of the of such palaeontological finds, but it is also limited by the presence oasis. Therefore, the rank of this geological heritage type is local. of more representative and world-famous locality of fossil whales The palaeontological heritage of the Siwa Oasis is linked to in Egypt, namely Wadi El-Hitan (Sallam and Ruban, 2017; Sallam E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160 155

Fig. 4. Stratigraphical type of geological heritage (representative sections of the Marmarica Formation): a e the contact between the Oasis Member and the Siwa Escarpment Member; b e the contact between the Siwa Escarpment Member and the El-Diffa Plateau Member.

Fig. 6. Sedimentary type of geological heritage: a e desert sand dunes, b e old Shali e et al., 2018b). Therefore, the rank of this geological heritage type is town built of kershief (see explanations in the text), c outcrop demonstrating diversity of sedimentary rocks of the Marmarica Formation. also local. The sedimentary type of the geological heritage of the Siwa Oasis is rather diverse. The main features attributed to this type are as represent a spectrum of sedimentary rocks and related processes follows. First, desert sand dunes occupy significant areas to the (like karst development) (Fig. 6c). Generally, the rank of the sedi- south of the oasis (Fig. 1a and b and 6a). Although such dunes are mentary geological heritage type is global being determined chiefly not uncommon in Egypt (Misak and Draz, 1997; Refaat and by the uniqueness of kershief and less by the uniqueness of desert Hamdan, 2015; Woronko et al., 2017) and entire North Africa sand dunes and microbial agent of sedimentation in saline lakes. (Bristow and Armitage, 2016), the dunes of the study area are very The palaeogeographical heritage of the Siwa Oasis is also diverse. typical to use them for solution of problems relevant to dune All subtypes of this type distinguished by Bruno et al. (2014) are morphology and dynamics (Livingstone et al., 2007) and dune age reported from this area. First of all, sabkha facies is known in the (Bristow and Armitage, 2016). Second, the Siwa Oasis hosts the old Siwa Oasis (Figs. 1 and 7a, b), although the term playa may be more Shali town (fortress) built from evaporite stones e so-called kershief appropriate in this case according to the de finitions of Briere (Rovero et al., 2009; Abdel-Motelib et al., 2015)(Fig. 6b). This ma- (2000). It should be added that despite of relatively wide distri- terial is made from salt taken from the pre-Quaternary, Quaternary, bution of this facies in the world, sedimentary formations dis- and recent salt lake deposits (see below). From the sedimentolog- playing it so representatively as in the Siwa Oasis are well-suitable ical point of view, diagenetic changes in the natural geological for recognition as geological heritage (Lokier, 2013; Habibi and material after emplacement into fortress constructions are of spe- Ruban, 2017). Abdel-Fattah et al. (2013) demonstrated that a cial interest. These were described in detail by Abdel-Motelib et al. broad spectrum of facies is represented in the mid-Miocene de- (2015). Apparently, the Siwa's kershief should be considered as posits of the Siwa Oasis, including fluvial facies and carbonate globally-unique feature. The Siwa Oasis is a global reference site platform facies. If so, the outcrops of these rocks give really unique (and, probably, the only site of such a kind in the world) for this opportunity to understand palaeoenvironments. As mentioned highly-specific sedimentary building material. Third, Taher and above, the Cenozoic deposits of the oasis yield rich macro- and Abdel-Motelib (2014) described sediment stabilization by micro- microinvertebrate assemblages (Fig. 3), and, thus, not only single bial mats and biofilms in the Aghormi Lake with specific sedi- fossil remains, but palaeoecosystems are represented there. Shell mentary structures such as microbial patches, gas domes, etc. accumulations and such phenomena as encrustation, bioerosion, Similar phenomena are reported from several (even many) saline etc. permit documentation of different taphonomic patterns in the lakes located, particularly, in arid environments of western North Siwa Oasis (El-Sabbagh and El Hedeny, 2016; El-Sabbagh et al., America (Pace et al., 2016), Atacama desert (Rasuk et al., 2016), East 2016). Representatives of the trace fossil Thalassinoides have been Africa (Scott et al., 2007), and Western Australia (Boggs et al., 2007). The microbial mats and the biofilms of the Lake Aghormi appear to be unique on the country-level (at least). Fourth, some sections

Fig. 7. Palaeogeographical type of geological heritage: a, b e sabkha deposits in the Fig. 5. Palaeontological type of geological heritage: vertebra of fossil whale skeleton southern Siwa Oasis, c e trace fossil Thalassinoides isp. from the Siwa Escarpment (Middle Eocene, northeast of the Siwa Oasis). Member, c e the Oracle Temple. 156 E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160 found in the Marmarica Formation (Fig. 7c), and their relative diversity and stratigraphically-controlled variation provide unique opportunity for improvement of the knowledge this ichnogenus (El-Sabbagh et al., 2017). Orabi et al. (2015) documented the larger benthic foraminiferal turnover at the EoceneeOligocene transition in the Siwa Oasis and concluded about its relevance to volcanism- triggered warming, not glaciation-related cooling as though to be have occurred globally (Zachos et al., 2001; Lear et al., 2008; Ladant et al., 2015; Passchier et al., 2017; Ruban, 2018). This makes the sequence with the established foraminiferal changes of international importance. In fact, rare places in the world exhibit palaeoenvironmental patterns that differ strikingly from the strong trends and, thus, “opposite” signatures of the well-known global events. Finally, the Siwa Oasis possesses some geoarchaeological heritage (Figs. 1b and 7d). The latter is important from the palaeogeographical point of view because of two reasons. First, it rep- resents human modification of natural landscape of the oasis. Second, this heritage permits discussion of natural determinants of Fig. 9. Geological heritage objects (hydrological and hydrogeological type) of the some key archaeological features (e.g., Shaltout et al., 2007a; b). Russian South taken as examples for comparison. Generally, many of above-mentioned palaeogeographical features of the Siwa Oasis taken separately appear to be unique on the only (Fig. 8b). The high uniqueness of the above-mentioned features is regional scale in comparison to the similar features known in the determined by their diversity, abundance in desert environment, other parts of Egypt (Sallam and Ruban, 2017). However, the and comprehensive representation of geological activity of water in presence of the unusual signature of the EoceneeOligocene event a “remote” desert oasis. Despite the presence of lakes in some other and the diversity of the palaeogeographical phenomena permit oases of Egypt, the rank of this geological heritage type in the Siwa attribution of the entire palaeogeographical type of geological Oasis seems to be national. heritage of the Siwa Oasis to national rank. To realize the true geological uniqueness of the lakes of the Siwa Oasis, it appears sensible to compare them with the well-studied lakes of the Russian South (a large region with chiefly semi-arid 4.2. Geology-related environmental features to arid conditions) and, particularly, the Big Tambukan Lake (2 km2) and the Big Yashalta Lake (~40 km2)(Fedorov et al., 2004, The hydrological and hydrogeological type of geological heritage 2015; Fedorov and Garkusha, 2017)(Fig. 9). The uniqueness of the of the Siwa Oasis is constituted by several surficial and subsurficial both lakes is determined by their hydrological properties and water objects. These include lakes and saline pools (Figs. 1a and presence of significant amounts of soft sediment known as thera- 8aed, Table 1), springs, and aquifers characterized in the works of peutic mud. The Big Tambukan Lake has salt water and possesses Misak et al. (1997), Aly and Benaabidate (2010), Abdulaziz and Faid significant amounts of sulfide mud rich in organic matter and (2015), Abd El-Aal (2016), and Aly et al. (2016). The El-Maraqi, Siwa, allowing microbial activity. This resembles phenomena established Aghormy, and Zeitoun lakes were formed as a result of excessive in the lakes of the Siwa Oasis (e.g., Taher and Abdel-Motelib, 2014). storage of pumped drain water from the surrounding cultivated The dynamics of salt balance in the Big Tambukan Lake reflects area, presence of deep springs, and seepage of groundwater from shifts in distribution of salt in lake water and bottom mud. The Big surrounding high lands. The Jaghbub, Shaiyata, Um El Ghezlan, Yashalta Lake has water with very high mineralization and signif- Temrah, and El-Ma'aser lakes were mainly formed due to a lot of icant amounts of sulfide mud. Temporal desiccation leads to deep springs on their bottom and upward leakage from the Nubian deposition of salt particles (Fig. 10) like this occurs on the shore of Aquifer through faults. Small hyper-saline pools occur near the lakes in the Siwa Oasis (Fig. 7 b and 8a,b). Generally, this brief Siwa and Zeitoun lakes, and these are known as El-Mallahat reference to the Russian South allows two inferences in regard to the uniqueness of the hydrological and hydrogeological type of

Fig. 8. Hydrological and hydrogeological type of geological heritage: a e salt lake near Zeitoun, b e El-Mallahat (hyper-saline water pools), c e El-Shaiyata Lake, d e Sitra Fig. 10. Salt crystal deposition on the surface of the desiccated Big Yashalta Lake Lake. (Russian South). E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160 157

development of locally-speciﬁc soils that deserve recognition as unique features. Further investigations are necessary to choose geosite (in the form of land plot) where these soils are best represented. The geomorphological heritage of the Siwa Oasis is moderately diverse. This includes landscape-dominating characteristic landforms (mountains and hills) formed by differential erosion of layered sedimentary rocks (Figs. 2 and 11a, b), sand dunes (Fig. 6a), as well as the unusual “mushroom-rock" in El-Qara (Figs. 1a and 11c). Undoubtedly, such landforms are unusual for the Siwa Oasis, but similar landforms are common in the other parts of Egypt (Plyusnina et al., 2016), and, consequently, their uniqueness is limited. The rank of this geological heritage type is only local. The last, economical geological heritage type established in the Siwa Oasis is linked to salt extraction at El-Mallahat (Figs. 1a and 12). The exploitation of salt resource is an evident peculiarity of the oasis, but similar salt production occurs in many parts of Egypt, and, thus, the rank of this type is only local. This type is linked strongly to two other types, namely sedimentary and hydrological Fig. 11. Geomorphological type of geological heritage: a e characteristic landforms of and hydrogeological types. Moreover, the above-mentioned ker- the Siwa Oasis, b e Gebel El-Mawta, c e "mushroom rock" in the El-Qara Oasis shief production in the historical times can be judged in the terms of (northeast of the Siwa Oasis). the local geology-related economical activity. This means that the essence of local salt resource changed in somewhat through time. geological heritage of the Siwa Oasis. On the one hand, similar Importantly, the value of the economical type of geological heritage water objects can be found in the other parts of the world, which of the Siwa Oasis can become higher in the future if the local salt fact decreases the uniqueness of the type. On the other hand, the resource will be used not only for salt production, but also for lakes of the Siwa Oasis exhibit really peculiar phenomena, the balneological purposes. For instance, bottom mud from the salt Big uniqueness of which is underlined by the uniqueness of compara- Tambukan Lake in the Russian South is actively mined for subse- ble water objects in the other, remote regions. quent use in local hospitals and spa centers because of its excep- The geothermal heritage in the Siwa Oasis is linked to the newly- tional therapeutic properties, and this material is also exported. discovered geothermal resource (Abdel Zaher et al., 2018). Its Such economic importance of this therapeutic mud increases the further exploration will lead to the appearance of geothermal site uniqueness of the geological site where it is mined. If the salt that will be really unique on local scale. resource of the Siwa Oasis can be used in similar way, the The pedological heritage reﬂects chemical properties and, uniqueness of the economical geological heritage type will increase particularly, salinity of soils in the Siwa Oasis (Abdel-Shafy, 1992; together with increase in the rarity of the geology-related Madani, 2005). The intense agriculture and the presence of saline economical activity. water bodies in the restricted oasis environment determine

Fig. 12. Economical type of geological heritage: salt extraction at El-Mallahat near the Zeitoun Lake. 158 E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160

5. Discussion categories of “users”, namely scientists, educators, and tourists. As shown by the bibliographical survey, the number of research arti- The establishment of nine geological heritage types and several cles about the Siwa Oasis published in international geoscience geosites in the Siwa Oasis (Fig. 1b, Table 2) indicates on significant journals has become bigger in the mid-2010s relatively to the potential of its geological heritage as a new kind of natural earlier times. This indicates on increase in interest in geological resource. The latter has two evident aspects. First, this is a heritage investigations on this territory. Undoubtedly, unique features resource deserving conservation. Second, this is a socio-economical considered in the present paper are in the primary focus of re- resource deserving exploitation. These aspects are discussed below. searchers. Some unsolved questions remain (e.g., discussion of geothermal potential e Abdel Zaher et al., 2018), and this interest will not disappear in the nearest future. Therefore, the geological 5.1. Conservation issues heritage of the Siwa Oasis is a significant resource for scientists.As for educators, the remote location of the oasis does not facilitate its The Siwa Oasis has been declared as a national protectorate in frequent inclusion into routes of geoeducational excursions. How- 2002 with the area of 7800 km2 subdivided into three sectors, ever, the availability of such features as representative mid- namely the eastern sector (6000 km2; Munqar Tabaghbagh, El-Arag Miocene sections, sequence with a typical signature of the well- Depression, El-Qara Oasis, Sitra Lake, El-Bahrien Lake, and Nomu- known global event, and El-Mallahat saline pools makes this ter- mesiya Lake), the western sector (1700 km2; Shaiyata Lake and El- ritory interesting for development of geoeducational programs Gerba Oasis), and the middle sector (1000 km2; the Siwa Oasis it- (Fig. 13a). self). The main purpose of this protectorate is to preserve natural Tourism is thought to be important activity for the Siwa Oasis, biotic and abiotic resources (animals, plants, and water), to and some relevant problems were discussed by Hatem (2007), conserve the unique geological formations, to contribute to sus- Amara (2010), Ayad and Ye (2013), and Tawfik (2016). Some infra- tainable development, to facilitate tourism growth, to increase structure is already available (Hatem, 2007)(Fig. 13bed). The local awareness about the importance of conservation of natural and hospitality industry is developing, but satisfaction of guests de- cultural heritage sites, and to promote education and scientific pends on their individual preferences. There are several hotels research. It should be added that the value of archaeological, his- ( “three-star" and non-classified) and lodges with a different service torical, and cultural heritage of the Siwa Oasis is well recognized quality. Only some of them provide Internet access and other (Hatem, 2007; Abd El-Aal, 2016; Farrag and Elalfy, 2016). The pro- “standard” services. Accommodation price is generally low, tectorate status by definition permits adequate conservation of the although in some cases additional services require extra payments. Siwa's geological heritage. Importantly, potential visitors may have problems with finding The brief inventory of selected geosites undertaken for the information about hotels and lodges in Internet because of low- purposes of the present study implies the absence of serious dan- development of on-line promotion of these facilities. gers for their natural state. However, some cleaning from debris The diversity and the high rank of some geological heritage and sand, as well as installation of some infrastructure objects (e.g., types, as well as the presence of several easily or relatively easily explanatory panels) and other “standard” geoconservation pro- accessible geosites (Fig. 1b, Table 2) exhibiting really unique cedures (see Prosser et al., 2006) would be required in the case of geological features (see above) permit development of geological geological tourism growth (see below). Moreover, archaeological tourism, i.e., tours and excursions aimed at visiting of geological objects need protection from natural deterioration under the in- heritage objects by “occasional” and “devoted” tourists. This kind of fluence of climate-related agents (Abd El-Aal, 2016). tourism is new, bit it has spread significantly in the world in the 21st century (Dowling, 2011; Hose, 2012; Ruban, 2015). It should be 5.2. Geological heritage resource in tourism and sustainable stressed that tourism development is considered as a possible development: oasis perspectives and insights from comparison to factor of the local sustainable development in the Siwa Oasis, and, the Russian South thus, exploitation of the geological heritage resource (in the form of its involvement in tourism programs) contributes to this develop- The value of geological heritage as a socio-economical resource ment. However, the potential of the geological heritage of the Siwa can be understood via finding its importance for three main Oasis as a significant resource for tourists is limited by two cir- cumstances. First, geological tourism is not well developed in Egypt. Second, the oasis is located in a remote place of the Western Desert. In such a case, it appears to be sensible to develop geological tourism in combinations with two other types of tourism, namely archaeological tourism (Ross et al., 2017) and industrial tourism (Jonsen-Verbeke, 1999; Yashalova et al., 2017), as well as with the

Fig. 13. Premises for geological tourism development in the Siwa Oasis: a e educa- tional ﬁeld trip for university students, b e recreational space around the Cleopatra's Pool, c e tourism infrastructure at the Siwa Lake, d e saline water as local therapeutic resource. Fig. 14. Possible combination of tourism types in the Siwa Oasis. E.S. Sallam et al. / Journal of African Earth Sciences 144 (2018) 151e160 159

Table 3 Travelling possibilities to the Siwa Oasis.

Program URL Visits to unique geological features and landscapes

Siwa Oasis Tour http://www.westerndeserttours.com/tours-services/siwa-oasis-4-days/ þþ Siwa Oasis desert https://ramsestours.com/desert-safari/siwa-oasis-5-days-4-nights/ þþ safari Siwa Oasis Tours http://egyptlastminute.com/siwa-oasis-tours/ þþþ Visit Siwa Oasis https://www.emotoursegypt.com/en/activity/61004/3-days-2-nights-tour-package-to-siwa- þþ oasis-from-cairo Egypt Siwa oasis tour* http://www.desertegyptsafari.com/tours/egypt-siwa-oasis-tour/ þþþ Short Break at Siwa https://www.memphistours.com/Egypt/Packages/Adventure-Desert-Safari/Siwa-Safari-From- þþ Oasis Cairo

This program emphasizes on unique geological features.

“ordinary” tourism (conventional tours and excursions in the Siwa 1) nine geological heritage types and several geosites are estab- Oasis) (Fig. 14). It should be added that there is a variety of possi- lished in the Siwa Oasis; bilities to travel to the Siwa Oasis (Table 3). 2) the most unique geological features of the Siwa Oasis are linked In fact, there is a good ground for combination of geological, to historical salt material usage, palaeogeographical patterns, archaeological, industrial, and “ordinary” tourism. This is the and hydrological and hydrogeological features; presence of such essentially complex attractions as old Shali town 3) the inventoried geological heritage is important natural built from kershief material and salt extraction site at El-Mallahat resource of the oasis that can be treated in nature conservation (Fig. 14), which can be interpreted in geological, archaeological, and socio-economical contexts; industrial, and cultural contexts. Moreover, some geology-related 4) the comparison to the Russian South implies that the value of phenomena (e.g., springs e Fig. 13b) have been used for tourism the studied geological heritage and its potential importance to and recreation purposes already, and they have served as signifi- sustainable development in the oasis can be bigger considering cant tourist attractions. Additionally, one needs to note that the possible therapeutic utility of lake salt and mud. geological, archaeological, industrial, and “ordinary” types of tourism overlap significantly with regard to their resource (Fig. 14). Acknowledgements For instance, geological features dominate significant part of the Siwa Oasis and the adjacent territory, and, thus, these occur almost The authors gratefully thank M.G. Abdelsalam (USA) for his everywhere where “ordinary” tours and excursions can be orga- editorial support, S. Jain (Ethiopia) and Z. Hamimi (Egypt) for their nized (Table 3). In the other case, significant part of geologically- thorough reviews, and I. Baghi (General Manager of Siwa Protec- unique features is linked to archaeological landscapes. On the one torate, Egypt), M.H. Henriques (Portugal), and W. Riegraf (Germany) hand, the noted combination will permit to avoid unprofitable for various help. This study was funded by the grant of the Russian separate development of specific tourism types and to promote the Science Foundation Project 17-17-01229. Siwa Oasis as a general tourist destination. One the other hand, this combination will diversify the local tourism offer. Importantly, the References considered combination is not just a proposal. Tourism offer at the Siwa Oasis already includes visits to unique geological features, Abd El-Aal, A.K., 2016. 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