Journal of Geographic Information System, 2011, 3, 373-381
doi:10.4236/jgis.2011.34036 Published Online October 2011 (
Copyright © 2011 SciRes. JGIS
GIS and Intra-Site Spatial Analyses: An Integrated
Approach for Recording and Analyzing the Fossil Deposits
at Casablanca Prehistoric Sites (Morocco)
Rosalia Gallotti1, Abderrahim Mohib2, Mosshine El Graoui2, Fatima Zohra Sbihi-Alaoui2,
Jean-Paul Raynal1,3
1Université Bordeaux 1, Bordeaux, France
2Direction d u Patrimoine, Institut National des Sciences de l’Archéo logie et du Patrimoine, Rabat, Morocco
3Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
Received June 3, 2011; revised July 23, 2011; accepted August 1, 2011
The Mio-Plio-Pleistocene sequence at Casablanca, covering the last six million years, is well known in sci-
entific literature. The variability and the chronology of the Acheulian sequence is documented by systematic,
modern and controlled investigations in various sites (Unit L and Hominid Cave at Thomas I Quarry, Rhi-
noceros Cave at Oulad Hamida 1 Quarry, Sidi Abderrahman Extension Quarry, Bear’s Cave and Cap
Chatelier at Sidi Abderrahman Quarry) which have taken place within the framework of the
Franco-Moroccan co-operative project “Casablanca”. In order to manage the excavation data and to explore
the taphonomic nature of Unit L, Hominid Cave and Rhinoceros Cave, where research is still in progress, an
approach combining a Geographic Information System (GIS) and spatial analysis techniques was developed,
incorporating all existing information produced from previous excavations and recent surveys of the sites.
The amalgamation of this data into a GIS has resulted in a digital database that allows the production of si-
multaneous or separate visualizations and analyses of the fossils, artifacts and geological materials within
their original spatial contexts and also permits intra-site spatial analyses that allow a co mprehensive investi-
gation of the site formation processes.
Keywords: Morocco, Casablanca, Prehistoric Archaeology, GIS, Intra-Site Spatial Analyses, Site Formation
1. Introduction
During the last few decades archaeological research has
been characterized by a remarkable increase in the use of
computerised techniques; in particular, GIS (Geographi-
cal Information System) softwares have gained special
favour firstly in providing systems for the management
of archaeological data, and secondly as a fundamental
tool for the interpretation of archaeological contexts. GIS
has long been employed in archaeological landscape
studies for inter-site analyses. In recent times, many ap-
plications aimed at the interpretation of prehistoric de-
posits have also been developed [1-8]. The close connec-
tion between the spatial location of widespread exca-
vated evidences and the analytical study of each individ-
ual find makes the use of computer spatial analysis
technologies especially useful in conjunction with GIS.
In this intra-site application field, GIS plays a decisive
role in the identification of the spatial trends of archaeo-
logical data through the contextual or selective treatment
of spatial variables. The sp atial distribution of finds in an
Early Pleistocene site is largely determined by post-
depositional disturbance phenomena affecting the ta-
phonomic environment, whether or not they are anthro-
pogenic, which always need to be taken into account in
any spatial interpretation [9]. One of the most complex
problems to solve is overcoming the difficulty of recog-
nizing the sequence of these alteration phenomena,
which often occur simultaneously, and are hence hard to
differentiate in an overall analysis.
Intra-site spatial analyses are important methodologies
for unraveling the formation and sequencing of prehis-
toric deposits, whose reconstruction provides decisive
evidence for the validation of subsequent deductive
analyses [10]. Thus spatial analyses make an important
contribution to the interpretation of prehistoric sites ex-
plored extensively using the stratigraphic method. In
consideration of the multiplicity of the above-listed fac-
tors, multidimensional analyses presently appear to be
the most advanced and appropriate techniques of spatial
investigation [11-17].
These considerations prompted our adoption of a
GIS-based investigation, integrated with spatial tech-
niques for the management and processing of spatial and
alpha-numerical data concerning the following sites of
the Casablanca region: Unit L and Hominid Cave at
Thomas I Quarry and Rhinoceros Cave at Oulad Hamida
1 Quarry. Investigations in these sites are still in progress
and this allowed us to design data management schemes
that followed each phase of the research rather than a
posteriori. In this paper we present the structure of our
information applications, the data recording system and
the types of analysis that we perform and envisage per-
2. The Archaeological Context
The Casablanca region on the Atlantic coast of the Mo-
roccan Meseta is rich in Palaeolithic sites p reserved in an
exceptionally well developed series of littoral deposits
(Figure 1) [18]. The Lower-Middle Pleistocene transi-
tion is well illustrated in Thomas I Quarry (Figure 2)
where the oldest lithic assemblages of the Casablanca
sequence are found in late Lower Pleistocene deposits,
circa 1 Myr in Unit L on an excavation surface of about
1000 m2, and consist of Acheulian artifacts made on
quartzite and flint [19]. In the same quarry, the archaeo-
logical assemblage of Unit 4 of the Hominid Cave,
where hominid fossils were first brought to light in 1994,
documents the Middle Pleistocene record. While this
cavity sheltered a population of hominids during the
early Middle Pleistocene, it was also frequented by a
variety of carnivores during the same period. Despite a
surrounding environment only sparsely tree-covered, an-
abundant mammal fauna was present in the area and this
favoured th e subsistence of both hominids and carnivor es.
The semi-arid conditions of the time were responsible for
Figure 1. Location map and position of the main Lower Palaeolithic sites excavated at Casablanca (A). 1, Sidi Abderrahmane
Grande Exploitation. 2, Sidi Abderrahmane-Cunette with Cap Chatelier and Bears Cave. 3, Sidi Abderrahmane-Extension. 4,
STIC Quarry. 5, Thomas Quarry I. 6, Thomas III Cave . 7, Thomas III “fissures”. 8, Oulad Hamida 1 (Rhinocer os Cave ).
Copyright © 2011 SciRes. JGIS
Figure 2. General view of the Thomas I Quarry.
the complex sedimentation and post-depositional proc-
esses present in the cave. Absolute dates place strati-
graphic Unit 4 between 360 and 470 kya, but more re-
cently, this has been pushed towards 500 kya by laser
ablation ICP-MS. Nevertheless, bio-stratigraphy and
litho-stratigraphy point toward s an even greater antiquity
Middle Pleistocene levels also occur in the Oulad
Hamida 1 Quarry, where Rhinoceros Cave has yielded a
rich collection of micro and macro mammals with re-
markably abundant remains of white rhinoceros, associ-
ated with a rich Acheulian lithic assemblage (Figure 3)
3. The Application
These sites, extensively excavated, yielded an enormous
quantity of lithic objects and faunal remains. Due both to
the extent of the investigated areas and the number of
finds, technological tools for recording spatial data were
found necessary during the excavation phases but more
importantly for intra-site spatial analyses undertaken to
elaborate on the locational information associated with
the finds. To manage the huge quantity o f data a GIS was
chosen because of its almost limitless possibilities for
recording alphanumerical and graphical data, of visuali-
zation, analysis and subsequent processing. We used two
GIS software products to perform different types of spa-
tial analyses. The logical structure of our methodology is
summarized in Figure 4.
3.1. Recording Archaeological Evidence
Documentation for the excavations at Thomas I and Ou-
lad Hamida 1 Quarries exists in two different forms: pa-
per archives recorded before the use of an electronic ap-
plication (2006) and data collected using an electronic
Figure 3. Top: General view of the Rhinoceros cave. Bottom:
Detail of the excavation.
information system. The amalgamation of these data was
necessary to create an information resource which could
be manipulated to manage all the classes of data simul-
taneously. The paper documentation consisted of a writ-
ten catalogue of the finds from the excavations accom-
panied by the relative plans. Th e first step was to co nvert
the written alpha-numerical data (the catalogue entry for
each lithic artifact or bone) to digital format. Microsoft
Access was used to create the alpha-numerical archives
(and is also used to collate new information). It was
chosen mainly for its simplicity of use in the creation of
tables and templates and especially because it permits the
use of personalized dictionaries, thus facilitating data
entry and assuring, at the same time, the homogeneity of
the archived data in its new form.
After the conversion of the paper alpha-numeric ar-
chives, we computerized the existing paper maps that
had been made for every square meter of the excavated
areas. The excavations were carried out within a grid of 1
× 1 metre squares, within which every single find had
been accurately positioned.
opyright © 2011 SciRes. JGIS
Figure 4. Conceptual scheme of the informatics application.
This grid was imported into MapInfo Professional,
referenced on non-terrestrial coordinates using a metric
scale and then translated into a vector format. We created
two local networks: one for Thomas I Quarry, including
Unit L and Hominid Cave (Figure 5), another for Rhi-
noceros Cave. Every paper map was scanned, imported
into MapInfo as a raster image and located in its proper
place in the appropriate local network using the coordi-
nates of the vertices of the corresponding squares.
Any object contained within the image was drawn as a
polygon and linked to the database through its inventory
number which is a unique key. It is also possible to view
any found object as a point thanks to the MapInfo Ex-
tract Coordinates utility, which can au tomatically extract
the x and y coordinates of the midpoint of a polygon.
The second step was to create an appropriate system
with which to record newly generated excavation data.
We chose a flexible structure using Total Station inte-
grated wi t h orthophotos.
Usually, we use Total Station to record point data of
archaeological objects on maps collating this type of
information. If the excavated area is particularly repre-
sentative in some way or portrays archaeological objects
of large dimension s, we utilize the orthophotos to record
such finds as polygons. We take a photo of each square
metre of the excavation and use RDF software to trans-
form it into an orthophoto. As with the documen tation of
earlier excavations, the orthophoto is imported into
MapInfo Professional, referenced, translated into a vec-
tor format and then every graphical object depicted is
linked to the database through its inventory number.
3.2. Processing of Spatial Variables
Both alphanumerical and graphic data are managed by
GIS software. MapInfo Professional is the principal
software used to elaborate thematic maps and sections
and frequency matrixes. Another principal software used
to elaborate thematic maps and sections and frequency
matrixes. Another GIS product, ArcView, was added to
our suite because of its capabilities in processing density
analyses. Combining alpha-numeric and graphic infor-
mation makes it possible to present diverse queries to the
database and to interrogate simultaneously the al-
pha-numerical data with its corresponding graphic ob-
jects. The results thus created are then saved as new ta-
bles and maps. It is thus possible to generate numerous
thematic ‘maps’ that present the object categories found
in the excavation, as unique categories as well as show-
ing their association with other selected categories or
types of information, thus allowing spatial comparisons
to be made between any number and variety of different
objects and/or data (Figure 6).
The huge number of finds discovered in the three sites
concerned makes it difficult to obtain accurate impres-
sions of their spatial distribution in any normal concep-
tual manner; so the topological features of GIS are used
to create maps derived from the data and present it as
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Figure 5. Local network with excavated areas at Thomas I Quarry.
frequency analyses, or to obtain density values and to
schematize the distribution trends (concentrations or
dispersals) of artifacts.
For maps recording frequencies, finds were grouped
and counted per square [13] using an SQL procedure
based on the topological overlay of the 1 m by 1 m ex-
cavation grid for each thematic level. This procedure
allows automatic calculation of the number of objects
whose central point falls within each square. The maps
thus obtained contain the total number of each category
of finds falling within each grid square. Frequencies in
these maps are expressed by ranges of standard values
delineated by ‘natural breaks’, a method that identifies
the break points by picking the position within each class
that best groups together similar values and maximizes
the differences between classes. The features are thus
divided into classes whose boundaries are set at the posi-
tion where a relatively big jump in the data value occurs
(Figure 7). By combining two or more frequency ma-
trixes, it is possible to compare the frequency of each
category per square metre and present the result graphi-
cally (Figure 8). To provide a rendering of object con-
centrations not linked to the spatial units defined by the
excavation grid, density maps were created. Points cor-
responding to the centroid position of each object were
exported into ArcView, where density plans were gener-
ated using Spatial Analyst. The density function calcu-
lates the number of points in a level over a continuous
surface. Thus, the occurrence and proximity of points is
highlighted through the generation of a new map of den-
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Figure 6. Thomas I Quarry—Hominid Cave, Locus 2. Thematic map of all remains.
sity values beginning from a given point. Values are ex-
pressed through density curves quantified on the basis of
a k-nearest neighbour distance that is smoothed using
Kernel Density Estimation (a fundamental data smooth-
ing operation where inferences about the population are
made, based on a finite data sample) (Figure 9).
The vertical distribution of finds is projected on lon-
gitudinal and transverse cross-sections which generally
correspond to a two-dimensional representation: by
ranging the values of x or y respectively on the abscissa,
and those of z on the ordinate, it is possible to plot the
projection of all finds and thus map these kinds of
cross-sections. This expedient is necessary because the
GIS packages lack 3D topology and consider z values as
attributes rather than as true spatial coordinates (Figure
opyright © 2011 SciRes. JGIS
Figure 7. Thomas I Quarry—Unit L. Frequency matrixes per square meter of all remains.
Figure 8. Thomas I Quarry—Unit L. Relationship among the frequencies of different categories of finds per square meter.
4. Conclusions
Systematic stratigraphic excavations, documented with
three-dimensional recording, and the use of intra-site
spatial analyses using GIS and associated systems proved
invaluable tools for analyzing the Acheulian sites at
Casablanca which are characterized by an extremely high
number of finds and by complex post-depositional
mechanisms. The integrated approach that we used per-
mitted us to record, follow and analyze each phase of the
research, from the first stage of recording information to
the later step of data interpretation. Our use of the sys-
tems mentioned allowed a more immediate management
of the data related to the spatial interrelations of fossils,
artifacts and geology through continuous evaluation of
all the attributes of distribution and analysis available in
opyright © 2011 SciRes. JGIS
Figure 9. Thomas I Quarry – Unit L. Density map of all remains.
Figure 10. Oulad Hamida 1—Rhinoceros Cave. Excavation 2009. S-N cross-section with the projection of all remains.
the various programs.
This model for handling large amounts of information
simultaneously has clear potential for storing and orga-
nizing the huge volumes of data generated by any exca-
vation and for illuminating and unraveling the complex
processes responsible for the formation of Palaeolithic
sites. The model developed for the Casablanca sites can
be broadly appli e d t o other si milar sites.
5. Acknowledgements
The authors thank anonymous readers whose comments
allowed us to improve this paper and Peter Bindon for
the revision of the English language. Excavations take
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place within the frame of the Programme Casablanca of
the Institut National des Sciences de lArchéologie et du
Patrimoine and are funded by Ministère de la Culture of
Morocco, Ministère des Affaires étrangères et eu-
ropéennes of France, Région Aquitaine and the Depart-
ment of Human Evolution of Max Planck Institute for
Evoluti onary Ant hropology at Leipzig.
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