e-SOTER Project General Assembly, Morocco 2011
areas: Germany, Laos, Thailand, Vietnam
Excursions: Australia, China, Germany, Hungary, Morocco, Thailand
Date: October 04 - October 07, 2011
eSOTER field trip went from Rabat to the Kariat Ba Mohamed region and
the Taza-Tahla region. The Kariat Ba Mohamed region is part of the
Pre-Rif domain. The Taza-Tahla region straddles three geological units:
the Fes-Taza couloir, the Rif and the Middle Atlas.
Figure 1: Field trip route and visited soil profiles in the Moroccan
Kariat Ba Mohamed region
The Kariat Ba Mohamed region is part of the
Pre-Rif domain. It is a group of complex geological formations, mostly
Cretaceous and Tortonian marly series. The complexity of the region
results from an extreme disorder of different sedimentary formations'
laying and from thrust and chip structure, knowing that the Pre-Rif
domain experienced the same orogenic phases as the Rif mountain domain.
Generally, the Rif mountain domain is a part of the Mediterranean
Alpine orogeny which results from the rapprochement of the European and
African plates. The climate is Mediterranean semi-arid in the South,
with a slight tendency to sub-humid climate in the North. Average
annual rainfall ranges between 500 mm and 600 mm with a slight
North-South gradient. The mean monthly temperature is about 12°C, the
mean minimum is about 5°C (during winter) and the mean maximum is about
39°C (during summer). The average annual evapotranspiration is 1500 mm
with a maximal value of 230 mm in July.
Soil type: Grumic, Calcic Vertisol (Eutric, Pellic)
Parent rock: marlstone (Triassic)
Position: N34° 19' 40.5'' W05°
10' 59.7''; Elevation: 117 m asl
Figure 1: Vertisol landscape (left), soil
profile of a Vertisol from marlstone, showing different subsurface
The visited Vertisol profile contained different subsurface features,
which are bounded by major slickensides. The bright subsoil material of
the right corner is part of a "chimney", whereas the part of the left
side grades into a "bowl". During a period of swelling, soil material
in the section of the "chimney" soil material is mainly pushed upwards,
while in the section of the "bowl" lateral shear stress prevails.
During dry season, the smectite-rich soil material is affected by
shrinking, leading to deep and wide cracks.Generally, Vertisols occur
at lower landscape position. Towards higher landscape positions
Vertisols increasingly integrate with Cambisols and Regosols.
Soil type: Vertic Cambisol (Calcaric, Eutric)
Parent rock: marlstone (Paleocene)
Position: N34° 25' 29.4'' W05°
14' 43.5''; Elevation: 178 m asl
Figure 2: Landscape with
Vertic Cambisols (left), soil profile of a Cambisol from marl (right).
The Taza-Tahla region straddles three
geological units: the Fes-Taza couloir, the Rif and the Middle Atlas.
The Fes-Taza couloir is part of the south Rif couloir that extends from
the Atlantic Ocean to the Mediterranean Sea. It contains Miocene marls
and some recent to ancient Quaternary deposits. The Rif unit takes
place in the north of the couloir where the first Rif hills occur and
constitute the marly pre-Rif zone. This marl zone lies as the foreland
of the autochthonous Rif and holds several facies: Trias with white to
reddish gypsum masses, Jurassic with flysch units, Early Cretaceous
with sedimentary klippes, Late Cretaceous with homogeneous
(trey-light blue) or motley (dark grey, light grey and red) marls,
Eocene with chert bearing white marls, Oligocene with light marls, Low
and Middle Miocene with marly lime and Late Tortonian with sandstone,
conglomerate and marls. The Tortonian also occurs as a marly matrix
called "Rif complex". The third geological unit of the Taza-Tahla
region unit is a part of the Middle Atlas and it is divided into two
sub-domains. The first one is the Middle Atlas causse, it is a tabular
structure with Lias limestones. The second one is the pleated Middle
Atlas, it is a succession of broken anticlinal ridges separated by
The climate of this region is highly variable, tending to aridity in
the East due to exposition, while the altitude is the influencing
factor in the Pre-Rif. Average annual rainfall varies strongly from
year to year, ranging from 199 mm to 1485 mm. Temperature is at its
maximum in July and august, reaching 40°C, and at its minimum between
December and February, reaching 5°C. Blanney-Criddle
evaportranspiration varies from 849 mm a-1 to 1559 mm a-1 with maxima
in July and minima in December. Insolation is 3000 h a-1 and dominant
winds are oriented either east-west or following the Inaouen valley.
Soil type: Calcic Kastanozem (Clayic, Chromic)
Parent rock: gravel (Quaternary) over marlstone (Miocene)
Position: N34° 05' 38.4'' W04°
32' 52.5''; Elevation: 325 m asl
3: Location of soil profile on a former river terrace (right). Soil
profile of a Kastanozem from gravel and marlstone.
Soil type: Calcic Kastanozem (Endoskeletic, Clayic, Chromic)
Parent rock: gravel (Quaternary) over limestone (Miocene)
Position: N34° 08' 26.5'' W04°
4: Former river terrace with Kastanozems. Soil profile of a Kastanozem
Soil type: Humic Calcisol
Parent rock: conglomerate (Miocene)
Position: N34° 13' 54.4'' W03°
Figure 5: Calcisol landscape (top left), soil profile of a Calcisol
from conglomerate (top right), conglomerate outcrop on a slope below a
plateau with Calcisols (bottom left), sheep shelter within the Calcic
horizon (bottom right).
Map of Morocco at 1:1M scale.
R., Iaaich, H., Zouahri, A., Douaik, A., El Ouadi, M., 2011. eSOTER
Project General Assembly. Morocco, 2011 October 4th-7th. Field book.