Exploration and Practice of Empowering Teaching Process of General Education Course in Gemmology with Artificial Intelligence

INTRODUCTION

Amber, a fossilized plant resin, has been preserved throughout geological time (Langenheim, 1969). Its unique chemical compositions allow for the exceptional preservation of biological inclusions in their three-dimensional, pristine, and minute details (Langenheim, 2003; Poinar, 1992). Amber occurs all over the world and its age ranges between a few millions and 320 million years (Mid Carboniferous) (Sargent Bray & Anderson, 2009).

Lebanon is well known for its numerous Mesozoic amber deposits (Azar, 1997, 2012；Azar et al., 2010; Maksoud & Azar, 2020; Maksoud et al., 2022). Leban on with its small territories and its multiple amber outcrops is relatively the richest country with amber. Most of the amber outcrops in Lebanon are Early Cretaceous [early Barremian (Maksoud et al., 2017)] in age (ca. 450 outcrops found to date), others are Late Jurassic (Kimmeridgian) [19 outcrops (Nohra et al., 2013) (Fig. 1)]. It is however noteworthy that a single rounded amber bead (from early Barremian origin) was found redeposited in an Albian marine deposit in Rwaysat Saoufar [Caza (District) Aley, Mouhafazet (Governorate) Jabal Loubnan, Central Lebanon].Anecdotally, another millimetric amber bead was found interspersed within the bone accumulation of a late middle Cenomanian fossil bird from Nammoura [Caza (District) Kesserouane, Mouhafazet (Governorate) Jabal Loubnan, Central Lebanon] (Dalla Vecchia & Chiappe, 2002). Approximately 10% of the land in Lebanon contains amber. Traditional Lebanese songs describe rightly Lebanon as the “mountains of amber”. Lebanon in several verses of the Bible was described as “land of the milk and honey”. Given the aforementioned reasons, we hereby proclaim Lebanon as the land of amber. Astonishingly, despite the numerous Lower Cretaceous amber deposits found throughout Lebanon, only 30 of these, all of which belong to the Early Cretaceous period, have been discovered to contain biological inclusions — 29 of which have already been published, while the discovery of a new outcrop in the Rashaya District on the 17^th of April 2023 will soon be published (Fig. 2).

Figure  1.  Map showing all Late Jurassic amber localities in Lebanon. Yellow dots represent the discovered outcrops. 1: El-Ghineh; 2: Ehmej-Aalmat; 3: Qartaba; 4: Tannourine El-Faouqa; 5: Harissa; 6: Ed-Doueir; 7: Arz Tannourine; 8: Hadath El-Joubbeh; 9: Bcharreh-Beqaa Kafra; 10: Beit Mounzer; 11: Qnaiouer; 12: Ehden (Mantra); 13: Ehden-Aaintourine; 14: Aaintourine; 15: Haouqa Ⅱ; 16: Haouqa I; 17: Haouqa Ⅲ; 18: Blaouza Ⅱ; 19:Blaouza I. (Map source is public and provided by Google Earth).

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Figure  2.  Map of Lebanon with Lower Cretaceous amber and fossil insects’ outcrops. Dark green areas indicate the distribution of the amber localities. Yellow circular spots indicate the emplacements of Lower Cretaceous amber outcrops with insects’ inclusions: (1) Mechmech (Ain El-Khyar); (2) Nimrin (El-Dabsheh); (3) Brissa; (4) near Bcharreh; (5) Beqaa Kafra; (6) Hadath El-Joubbeh; (7) Tannourine; (8) Mazraat Kfardibiane; (9) Ouata El-Jaouz; (10) Bqaatouta (El-Shqif); (11) Baskinta (Qanat Bakish); (12) Daychouniyyeh; (13) Kfar Selouan; (14) Kfar Selouan (Khallet Douaiq); (15) Mdeyrij-Hammana; (16) Falougha; (17) Ain Zhalta; (18-19) Ain Dara (two localities); (20) Sarhmoul; (21) Roum-Aazour-Homsiyeh; (22) Bkassine (Jouar Es-Souss); (23) Wadi Jezzine; (24) Maknouniyeh; (25) Rihane; (26) Esh-Sheaybeh; (27) Bouarij; (28) Aita El-Foukhar; (29) Ain Zhalta (Ain Azimeh); (30) Tannoura.

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For a considerable amount of time, prior to recent discoveries (primarily in the Dolomite mountains of Italy, as reported by Schmidt et al., 2012), Lower Cretaceous amber in Lebanon was regarded as the oldest known amber to contain biological inclusions.Today, even if it no longer retains the record of containing the oldest amberiferous biological inclusions, along with Syrian (Choufani et al., 2015), and Jordanian (Kaddumi, 2005) ambers, both of which are considered as coeval with Lebanese lower Barremian amber, it is still among the most important for the study of arthropod evolution, as the period of its formation is contemporaneous with the appearance of flowering plants (angiosperms) and the associated newly evolved ecosystems. Moreover, it documents the initial diversification of the modern entomofauna and the disappearance of some archaic insect groups (Azar, 1997, 2000, 2007, 2012; Azar &Nel, 1998; Poinar & Milki, 2001; Azar et al., 2010).

HISTORY OF AMBER IN LEBANON

The Phoenicians [an ancient civilization (with period of greatest prominence approximately 1550 to 300 BC) that ruled the Mediterranean before the Greeks and Romans and originated in the Levant especially Lebanon, in the west of the Fertile Crescent] were most likely the first tradesmen of amber in the Mediterranean (McDonald, 1940). It is believed that between the sixteenth and fourth centuries BC (but especially between the eighth and fourth centuries BC), the Phoenicians pioneered the Amber Route (Fig. 3), a maritime trade route from the Mediterranean to the shores of northern Europe, specifically the Baltic area. This route allowed for the exchange of golden fossil resin for bronze.

Figure  3.  Trade (maritime road) in the ancient Mediterranean between 8^th and 4^th centuries BC. The regions shaded in purple were under the Phoenician influence. (Map source is public and provided by Wikipedia).

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According to some authors based on recent archeological discoveries, amber was collected in Phoenicia (today Lebanon, the Syrian coast and northern Israel) and marketed in the Middle East by Phoenicians until the Baltic amber, which is of better gemological quality, became accessible (Williamson, 1932; Nissenbaum, 1975) (Fig. 4).

Figure  4.  Amber beads from Roman times found in different archaeological sites in Beirut and Beqaa valley.

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The mythical foundation of the ancient metro-polis of Tyre (southern Lebanon) is correlated with amber, where it is believed that this biblical city was founded on two ambrosian rocks (Fig. 5). According to the legend, two wandering ambrosian rocks floated over the sea; between them was a burning olive tree with an eagle perched on top of it. A snake was entwined around the tree; both eagle and snake lived in harmony. Melqart (also Melkarth or Melicarthus) [son of Baal (or El, Ruler of the Universe), tutelary god of the city-state of Tyre, king of the underworld, protector of the Universe] ordered the native population to build a ship and follow after the wandering rocks (Fig. 6).The god’s oracle was to sacrifice the eagle and pour its blood on the ambrosial rocks so that these later would stop wandering, indicating the place for the foundation of the city of Tyre. The myth is symbolically described on several of the coin types of the city, minted under the reigns of several Roman Emperors like Elagaba-lus (218~222 AD) (Fig. 6b, 6f, 6g), Gordian Ⅲ (238~244 AD) (Fig. 6c, 6h, 6i), Trebonianus Gallus (251~253 AD) (Fig. 6d, 6j) and Valerian I (253~290 AD) among others (Fig 6e, 6k).

Figure  5.  (a) Tyre during the Phoenician time, as imagined by artist (500 Questions, 2023); (b) Tyre today (Nsf2003, n.d.); (c) Ancient depiction of the fortified island city of Tyre, circa 837 B.C., illustrating its walls and towers (Evidence-For-The-Bible, n.d.).

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Figure  6.  (a) The Melqart stele (National Museum of Aleppo), also known as the Ben-Hadad or Bir-Hadad stele, is an Aramaic stele created during the 9^th century; (b) Roman Emperor Elagabalus (218-222 AD); (c) Roman Emperor Gordian III (238-244 AD); (d) Roman Emperor Trebonianus Gallus (251-253 AD); (e) Roman Emperor Valerian I (253-290 AD); (f) and (g) Roman coin minted in Tyre under the reign of Emperor Elagabalus (218-222 AD), Æ 27 mm; (h) Roman coin minted in Tyre under the reign of Emperor Gordian III (238-244 AD), Æ 29 mm; (i) Roman coin minted in Tyre under the reign of Emperor Gordian III (238-244 AD), Æ29 mm; (j) Roman coin minted in Tyre under the reign of Emperor Trebonianus Gallus (251-253 AD), Æ25 mm; (k) Roman coin minted in Tyre under the reign of Emperor Valerian I (253-290 AD), Æ27 mm. The reverses of all those coins represent the mythological foundation of the City of Tyre (in Southern Lebanon), as reported in the Dionysiaka by Nonnos of Panopolis.

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The word “Lebanon” derives from “Louban” which has two meanings: white, in relation to the Lebanese snowed mountains; and incense, maybe in relation to cedars’ resin used by Pharaonic Egyptians for mummification, or perhaps simply to amber. It is likely that the Slavic word yantar, which is one of the words that is used for amber, could be of Phoenician origin (Szwedo, personal communication, 2022 November 5^th).

In modern time, although the presence of amber in Lebanon has been documented several times since the beginning of the nineteenth century (Desmarest, 1816; Kastner, 1831; Botta, 1831; Brocchi, 1843; Russegger, 1843; Ritter, 1854; Fraas, 1876, 1878; John, 1878; Cuinet, 1896) and the twentieth century (Zumoffen, 1926; Dubertret, 1950, 1951, 1955), it is only late in the 1960s that fossil insects were recorded in this material (Schlee & Dietrich, 1970; Dietrich, 1976; Hennig, 1970). As a matter of fact, people in Lebanon during the eighteenth and nineteenth centuries were not very interested in the amber by itself (because of its bad gemological quality), but in the more or less abundant coal associated with amber layers, as a source of energy. The amber was cited by the above nineteenth century authors occasionally while describing the coal or lignite extractions in the mines. The first geological maps of Lebanon made by Botta (Fig. 7a), then by Russegger (Fig. 7b), had an aim to locate the lignite and iron mines in order for them to be exploited for energy and industry.

Figure  7.  (a) Paul-Émile Botta, a French archaeologist (1802-1870)(Ashurbanipal Library Project, 2013); (b) Joseph Russegger (or Joseph Ritter von Russegger), an Austrian geologist (1802-1863)(Austria-Forum, 2011); (c) Oscar Fraas (or Oscar Friedrich von Fraas), a German geologist (1824-1897)(Wikimedia Commons., n.d.)

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In 1962, Aftim Acra (Fig. 8a), while leading a fossil hunting expedition in the mountains in Daher-El-Baydar (Central Lebanon) and accompanied by his son Fadi and Raif Milki, found a piece of amber. From then till the 1970s they found several amber outcrops including the well-known one of Bkassine (Jouar Ess-Souss) in Jezzine area, which was discovered independently and at the same time by a German expedition organized between 1968-1969. The German expedition was carried out after M. Warth gave Willi Hennig (in 1967) some samples of amber from Bkassine (Southern Lebanon) kept in the Ludwigsburg collection in Stuttgart Museum. These samples were the remains of the collection of Oscar Fraas (1824-1897) (Fig. 7c), a German geologist who was tasked by Rustem Pasha (Rustem Mariani 1810-1885) (Fig. 8b), the Italian governor of Mount Lebanon (1873-1883), to study the geology in order to find coal mines. From 1994 till the present day, a total of approximately 450 amber deposits have been discovered, spanning from the Late Jurassic to the Cenomanian period.

Figure  8.  (a) Professor Aftim Acra (1922-2007), photo from Reem Acra; (b) Rustem Pasha (or Rustem Mariani, 1810-1885), the Italian governor of Mount Lebanon (1873-1883)(Wikipedia, 2022, October 6)

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GEOLOGICAL SETTINGS

Amber from the Late Jurassic in Lebanon (19 sites, all located in the northern part of Mount Lebanon (Azar et al., 2010; Nohra et al., 2013) is found in volcanolateritic deposits (volcanic Kimmeridgian, symbolized as βJ6 in existing geological maps of Lebanon). The amber is found in lens of lignite mixed with laterites and pyrite that occupy pits in volcano-basaltic complex soil (Fig. 9a, 9b).

Figure  9.  (a) Jurassic amber from Aaintourine; (b) Jurassic amber from Beit Mounzer.

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Amber from the Lower Cretaceous (Fig. 10a, 10b) in Lebanon appears in silt sediments in the form of dark shales with lignite and fossil plant debris in mainly three intervals of the sandstone dubbed “Grès du Liban” Formation. Their deposits are interpreted as corresponding to siliciclastic coastland estuarine palaeoenvironments based on the occurrence of bioturbation, echinids and bivalves in the transgressive marine layers and that of amber and lignite in the regressive layers.

Figure  10.  (a) Early Cretaceous amber from the newly discovered (17^th April 2023) fossiliferous outcrop of Tannoura; (b) Early Cretaceous amber from the fossiliferous amber outcrop of Aita El-Foukhar.

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The entomofauna association of the amber inclusions indicates a dense and dark amber producing forest with warm tropical climate, which is also corroborated by palynological data (Azar et al., 2011).

For a long time, the age of Lower Cretaceous Lebanese amber remained subject to debate and imprecision. Various authors dated the outcrops as Neocomian-Aptian (Zumoffen, 1926), Neocomian-Early Aptian (Dubertret & Vautrin, 1937), or Valanginian-Hauterivian in age (Schlee & Die-trich, 1970), encompassing a wide range spanning the entirety of the Early Cretaceous interval, with the exception of the Albian and potentially the late Aptian. In light of recent, thorough stratigraphic research, it has been determined that the Lower Cretaceous amber in Lebanon can be attributed to the early Barremian age (Granier et al., 2016; Maksoud et al., 2017; Maksoud et al., 2022).

LEBANESE AMBER INCLUSIONS

The most fascinating aspects of the Lebanese amber are the abundance and the outstan-ding preservation of the biological inclusions. In addition, the Lebanese amber holds significant importance among scientists, as it hails from the Lower Cretaceous era—a time when dinosaurs roamed the earth and flowering plants (Angiospermae) made their debut, marking a pivotal moment in plant evolution as angiosperms make up approximately 80% of all the known green plants now living. While the relationship between terrestrial arthropods (especially insects) and plants is so keen, it is logical that if we want to understand the origin of all recent and modern ecosystems, we have to go back to the epoch of their starting point, i.e., the Lower Cretaceous. Moreover, no intense terrestrial fossil records have been corresponding to this era except for the Lebanese amber, which increase significantly the uniqueness and exceptionality of this material. Inclusions can be found in one in every 25 to 30 pieces of Lebanese amber. This amber contains mainly arthropods and rarely includes vertebrate remains (Fig. 11). Among arthropods, Hexapoda are largely dominant and most of the orders (23 to date) are represented. To date circa 265 taxa have been described and named from Lebanese amber, whereas other inclusions are still waiting their identification.

Figure  11.  (a) A Chironomidae dipteran (non-biting midge) parasitized by an Acari (in the abdomen); (b) Lebanotermes veltzae Engel, Azar & Nel, 2011, Isoptera (termite), the oldest social insect in amber; (c) Yuripopovina magnifica Azar et al., 2011, a representative of the pentatomomorphan extinct family of Yuripopovinidae; (d) Scatopsidae dipterans in copula, the oldest preserved mating pair in amber; (e) The oldest Acari in amber; (f) The oldest Liniphiidae spider in amber; (g) Baabdasaurus xenorus, Arnolds et al., 2002, the oldest reptile in amber; (h) The oldest feather in amber; (i) The oldest pupillid snail.

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A single piece of amber can contain one or several inclusions. Some of those that were found alone may provide important indirect hints of the presence of other organisms, or reflect a specific habitat or palaeogeography. Regarding the specimens where several inclusions (or syninclusions) are found together, some of them are present only in a random manner, but a considerable number of them are assembled for an ecological behaviour mating or parasitism, etc.

Some inclusions can provide indirect evidence of specific habitats, or palaeoclimate. For example, chironomids (very common and diversified Diptera in the Lebanese amber), limoniids, tipulids and psychodid flies, caddisflies (Trichoptera) provide evidence of aquatic or very humid habitats. In general, most of the Lebanese amber inclusions reflect a hot, dense and humid forest environment. The information given by the whole inclusions corroborate the data set by the palynology: the palaeoenvironment of the amber deposits corresponds to a tropical dense, warm and humid forest with an intense complex fluvial system, all occurring close to the sea (Dejax et al., 1996, 1997) (Fig. 12). In addition, most of the fauna entombed in the Lebanese amber represent organisms living on the lower to mid part of trees. This could be explained by the fact that this type of fauna has more chance to be trapped, since normally all the resin drops falling down from the tree pass inevitably and more frequently by this area. The study of the different inclusions allowed a hypothesized reconstruction of the ancient terrestrial ecosystem (Fig. 12).

Figure  12.  Reconstruction of the Lebanese amber forest during the Early Cretaceous.

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CONCLUSION

For countless centuries, amber has captivated the minds of many and will undoubtedly continue to do so. It constitutes a wonderful “natural time capsule” as termed by Ross(1998, 2010), and an original material that not only preserves superb biological inclusions in their pristine three-dimensional details, but also aspects of their life mode and ecology. Life forms preserved in amber increases significantly our knowledge of palaeobiodiversity, palaeoenvironment, and palaeoecology, and gives the amber its attribute of an exceptional “window to the past” given by Grimaldi (2003).

Lebanese amber contains many extinct families (some of them are known only from Lebanon) and the records of the oldest representatives of many modern families of terrestrial arthropods. In most cases, Lebanese inclusions constitute the “missing links” between the old fauna and the modern one. The study of the Lebanese amber inclusions is to date the only one that gives a clue in determining the North-East Gondwanan biodiversity and environment of the extremely significant Lower Cretaceous period. Recent findings of diverse and plentiful fossiliferous amber outcrops in Lebanon provide a promising opportunity to significantly enhance our understanding of the past. Lebanon that holds 10% of its land with potential amber outcrops, was described several times as the land of milk and honey, we herein baptized it also as the country or land of amber.

Endeavors are currently underway to classify the precious natural resource of amber as a part of the World Heritage list. The different Lebanese outcrops are not yet officially protected against vandalism. The loss or looting of these sites would undoubtedly constitute a grave blow to both human history and scientific understanding.