Inventory of geodiversity in the Zat Valley

INTRODUCTION

 

A reconnaissance field survey was carried out by members of the dept. of Geology at UAB in November-December 2015 with the objective to identify the main lithologic units and tectonic structures. 30 samples were collected along a N-S profile following the valley. A second field survey was carried out in June 2016, and another 40-45 rock samples is being studied. Third field survey took place in the Zat Valley in June-July 2017, with the objective to investigate the constitution, to delimit the extent, and to remark the singularities of each geologic unit in terms of natural heritage.

 

The Valley of the river Zat from the geological point of view as well as its biodiversity has remarkable assets, not only material but also cultural, to be able to present its candidacy to the UNESCO to, in the future, be included in the list of Geoparks, always and when the responsible Moroccan authorities take the initiative to start the process involving a long and complex work.

From the point of view of geology, the River Zat Valley is located in the central part of the Moroccan Atlas chain, where the highest mountainous heights of the chain are located. Therefore, the orogeny of the chain can be applied to the River Zat Valley, as we explained in the mid-year report for 2016. However, the various missions carried out in 2016 and 2017 allow us to establish various conclusions prior to the annual report, which must be completed with the missions scheduled throughout 2018 (April, June and maybe September). The following points have already been established:

  • A long geological history represented, from Precambrian to Cenozoic (pedagogical Atlas geology)
  • Diversity of rock types and processes, igneous, metamorphic and sedimentary • Pedagogic and accessible exposures of sedimentary rocks
  • Tectonic evolution can be uniquely deciphered by well-exposed:
  • 1) Syn-sedimentary extensional faults of the rifting stage (Triassic)
  • 2) Folds and thrusts of the Atlas orogeny
  • Well-expressed relationships geological substratum-vegetation types
  • Exceptional landscape value (including human-landscape interactions)

In terms of geological and natural risks, the Cerdan Eng partner has identified various types, most of them associated with landslides and climatic causes. A detailed description is specified in the bi-annual report sent to the EC at the beginning of the year 2017.

Specifically in the Zat River Valley we can identify numerous types of rocks, which we have selected and studied by optical microscopy, various geological structures such as faults and overhungs, geomorphological landscapes, alluvial formations, etc. all this makes the valley a good educational example for geological visits that, of course, should be shown at specific points to inform visitors, through panels in various languages, brochures, videos, etc. It is necessary to be able to collect samples of the various geological materials in order to be shown in a local museum (of the mountain museum type), the same for real geological and / or natural risks as well as their concrete effects, detailed by Cerdan Eng.

A separate case is the Yaggour plateau, at more than 3,000 meters above sea level, where there are abundant petroglyphs that constitute a major point of interest that must be protected and preserved. This geological and cultural value should constitute a geo-site in a future geo-park.

Petrological description of geological samples © Geopark-H2020
Petrological description of geological samples © Geopark-H2020

 

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STRUCTURAL GEOLOGY and STRATIGRAPHY

 

The Zat Valley represents a SE – NW deep incision in the northern slope of the High Atlas mountain belt, originated by the Zat river long-lasting erosion that allows the outcropping of a complete series of materials ranging from the Proterozoic (~ 2500 Ma), throughout the Mesozoic (~ 250 Ma) up to the Late Terciary ( ~4 Ma). The begining of the Mesozoic records the individualisation of elongated extensional basins that were filled with thick series of red sandstones supplied by the erosion of the preexisting basement crystalline materials. These red sandstones (Oukaimeden formation) are expectacularly shown as dramatic cliffs in several parts of the valley. All the Mesozoic and Terciary materials are folded and faulted by Atlasic (Alpine)-age deformation plus upwelling of the mantle during the Late Terciary (~ 30-10 Ma). This deformational event produced the local thrusting of the Proterozoic crystalline materials (f.i. the Meltsene thrust) onto those of the Mesozoic and has been responsible for the present more-than-4000 mts high relief of the High Atlas mountain belt.

 

PETROLOGY AND MINEALOGY

 

Overall, a detailed sampling has been made of the pre-Mesozoic basement crystalline rocks collected along a transect following the ZAT Valley. The sampling has been carried out in three different campaigns during 2016 and 2017 which have supplied a total of 108 samples. On collecting samples, we have payed particular attention to sites showing contact (intrusive) relations between the different outcropping rock types; within these sites we have collected all the appearing rock varieties, and it is worth noting that in several occasions we have collected single samples that contain the contact between two different rock types. For these particular samples we have made more than one single standard petrographic thin section or even a large petrographical in section in order to work out the precise nature of this contact. All the samples have been studied under the petrographic microscope at the Universidad Autónoma de Barcelona -description of each of the samples plus accompanying microphotographs of some of them together with field photos and UTM coordinates of the sampling sites will be supplied and presented at due moment.

 

BIODIVERSITY

 

The main goal of the research group, integrated by around twenty junior and senior researchers, from ICTA-UAB is to promote the interdisciplinary environmental research considering the transfer of knowledge as a cross-cutting issue in all of its research lines: Global Change, Biodiversity and Natural Protected Areas; Urban Biodiversity; Monitoring of socioecological indicators in the Mediterranean river basins; Environmental Education and Scientific Communication.

The group is leaded by Prof. Martí Boada, member of the International Committee for Education and Communication of IUCN (International Union for Conservation of Nature); Member of the Spanish Committee of UNEP (United Nations Environment Programme), and member of Spanish Man and Biosphere Program (UNESCO). Among most relevant recognitions, he has received the Global 500 UN Award (1995) and The National Environmental Prize (2003).

3 fieldwork campaigns occured:

  • November 2015: Objective: to put in value the biodiversity and landscapes of the Zat Valley through its patrimonialization
  • July 2016: Objective: to gather socioecological data in order to put in value the biodiversity and landscapes of the Zat Valley through its patrimonialization
  • July 2017: Objective: to gather data in order to put in value the biodiversity and landscapes of the Zat Valley through its patrimonialization and to identify the (cultural) ecosystem services related to the Valley though interviews with local people.

Tasks:

  • Protected areas
  • Biodiversity conservation
  • Socio-environmental services
  • Establishment of global change indicators
  • Pedagogic information
Inventory of mammals and birds for biodiversity conservation ©Conservation, Biodiversity and Global Change (UAB)
Inventory of mammals and birds for biodiversity conservation ©Conservation, Biodiversity and Global Change (UAB)

 

PALAEONTOLOGY

 

In November 2016, three missions of prospecting and inventory of the paleontological heritage were carried out within the framework of the Geopark Project H2020. The first two one-day missions each in the region of Larbat Tighadwine (3/11/2016 and 5/11/2016) and a third mission of ten days in the Argana basin in the Western High Atlas (8 to 18/11). These missions were aimed at: searching for Palaeozoic fossil plants, Permian and Triassic vertebrate remains and visiting a site with footprints of dinosaurs. Main results:

  • Over 20 specimens of fossil plants have been collected and deposited in the collections of the Museum of Natural History of Marrakech. These specimens, after analysis, will be used for the exhibition project as part of the collection (geological history and paleoenvironments of the Zat Valley)
  • More than a dozen localities with remains of tetrapods were located. Around 50 remains of fossil vertebrates were collected and deposited at the Museum of Natural History of Marrakech. Preliminary examination of some remains allows us to attribute them to groups of vertebrates unpublished in Permian of Morocco, procolophonides and gorgonopsiens. If their presence is confirmed, it will be the first mention of these faunas in North Africa.

 

ARCHAEOLOGICAL RUPESTRIAN HERITAGE

 

The High Atlas is of major interest for the study of Moroccan rupestrian art. The rupestrian sites are particularly known for the engravings dating back to metal ages. Yet, in some sites, rupestrian art expression has continued for longer periods until medieval ages and later but remain largely unknown and unstudied today. Many sites in the high atlas and namely the Yagour plateau are the product of millenniums of graphic accumulations that associate engravings that date back to different and historically distant periods. The rupestrian sites of the High Atlas are all located on the best pasture highlands at 2000 metres height which managed as agdal (pastoral territories that are established as “no go” areas by local communities in spring). Paleo-climate data reveal a sudden drought after the humid episode of the Sahara. This dry period which took place in many phases starting from the third millennium before our era seem to coincide with the appearance of the engravings in the High Atlas. The Yagour plateau is located on the Toubkal massive at a height of 2500 meters and covers an area of 14×20 km.

The rupestrian heritage of the Yagour plateau should not be considered as endangered heritage as to now. There have been some destructives actions so far; namely the highly mediatised “Sun Disk of the yagour” which has caused strong feeling in Morocco, but it appeared that these had no religious motivation as it was initially suggested. On the other hand, some engravings, with clear sexual connotations, could be condemned in the present context. That is probably the reason behind the destruction of the anthropomorphic engravings of « l’enclos des fiancés » (fiancés enclosure), and which was recorded for the first time during the expedition of 2015 directed by M. Bailly and reported to the Moroccan authorities thanks to the presence in this expedition of A. Lemjidi, a member of the CNPR. This station was used for female offering rituals for the sake of marriage or fecundity, which is not in conformity with the orthodox islam in practice.

Aside from these problems, maintaining the traditional life mode and the ‘no go’ system as represented by the adgal are the best guarantee for the conservation of the sites’ integrity. The increasing interest of Moroccans for their archaeologica l heritage and the governmental policies for sensitisation and education of isolated rural local populations are very positive indicators for the future of the engravings site.

In addition, the conservation and preservation of the sites depend on a pyramid system, starting by the Ministry of Culture to the local relays and association networks which enables the flow of information and the transmission of conservation measures. The situation of tangible cultural heritage in Morocco is more favourable than in many other countries in the region.

 

photography of the details in two engraved knifes ©A. Ewague
photography of the details in two engraved knifes ©A. Ewague

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