Hi, today I’d like to discuss
about our recent visit to the Nuraghe s’Uraxi
located in the territory of Lasplassas in Sardinia.
We generated a series of aerial maps
using a DJI Inspire 1 drone
with an X5R camera mounting
the standard 15mm lens
and with the help of an app called DroneDeploy.
I will walk you through the mapping process
and also discuss how aerial photography can
be a great tool for archaeological surveys.
Our relatively short trip starts
from the town of Barumini,
known for the UNESCO archaeological site Su Nuraxi.
Last year we did a tour around several nuraghi
in the territory of Barumini
and today I’d like to discuss about
what could be a very large nuraghe
potentially surrounded by a village.
After only 3 Km drive from Barumini,
we reach Las Plassas,
which is the ideal centre of the Marmilla region.
Las Plassas is known for its castle,
which was built on a conic hill,
probably in the 10th century.
The castle belonged to the Giudicato di Arborea,
when Sardinia was an independent state,
and its function was mainly defensive.
From Lasplassas we take a dirt road
towards south-west
and we reach the nuraghe s’Uraxi after 10min.
This nuraghe has not been excavated yet,
so we thought it would have been very interesting
to take some shots from above.
In the past years there has been a kind of
revolution in archaeology,
virtually allowing archaeologists to see
through the ground without digging.
In this sense, drones are particularly interesting.
In fact with a drone you can take multiple images
from different positions
and then stitch these images together
to create a huge georeferenced map.
Obviously the best solution to have an idea
of what is buried underground
would be to use advanced tools
such as multispectral cameras
or ground penetrating radars.
However, something can be done even
with a simple RGB camera.
Soils define how plants grow
and can be affected by
man-made features buried underground.
Variations in the density
and the colour of the vegetation
are often referred as “cropmarks”.
To generate a large aerial picture of the site
we used a trial version of the DroneDeploy app.
This app helps the drone raster scanning the area
and then collecting hundreds of pictures,
which are georeferenced.
These images can be then uploaded
to the DroneDeploy servers,
which are then merged into a massive geoTiff
in this case, with a resolution of about 2cm per pixel.
It is also possible to generate a 3D model.
However, in order to do so, you will need to collect
more images from different angles.
The images again are stitched together by
the DroneDeploy software
and then can be visualized
from the DroneDeploy website.
You can also download a 3D model.
Another map that can be extracted is the NDVI
or Normalized Difference Vegetation Index
NDVI is used to assess the plant health
and can also highlight the presence of cropmarks.
However for NDVI you will need a NIR camera.
A similar index that however
works on the RGB channels
is called VARI
and again can give an idea
of the presence of cropmarks.
As you can see here there are areas
suggesting the presence of structures underneath.
We cannot be sure on the nature of these structures,
which could be rocks as well as walls.
So we decided to show this data to
one of the most prominent archaeologists in Sardinia.
We met with Dr. Giorgio Murru
at the museum of Las Plassas called MudA.
Nuraghes are ancient megalithic stone towers.
They were built during the Bronze Age (1500-1200 BC)
without mortar
and were held erect by the sheer weight
of their roughly shaped stones.
After showing him the aerial photos
of the nuraghe s’Uraxi
we asked him to comment a bit on the architecture
and on the age of this site.
We know that this is a large nuraghe
made of several towers,
a complex nuraghe.
These towers will need to be
carefully studied after an excavation.
This nuraghe was probably built between the
Intermediate Bronze Age
and the beginning of the Late Bronze Age.
We then asked him to comment on the variations
in the density of the vegetation in this site
and the presence of positive or negative cropmarks.
These elements are fundamental for understanding
the presence of potential walls or building remains,
such as huts surrounding the nuraghe.
We should also consider that this hill is
made of marlstone
and that this calcite soil
can influence the vegetation.
The rock used for the construction of s’Uraxi
is a Miocene marlstone,
three milion years old,
also in the arenaceous variants,
which characterise not only this nuraghe
but also other nuraghi in the Marmilla region.
It is difficult to know exactly
what the function of the nuraghi was.
Today, we should think
of nuraghi as part of a system.
We cannot isolate them.
We should see them as part of the territory,
where each of them could have had its own function.
The location of s’Uraxi
can be considered
as sort of lockout post controlling
a penetration route from the river
to this hilly upland.
We then asked him to comment
on the positive outcomes
from an excavation of such a large site.
An achaelogical excavation is always science.
Science should give answers.
It should add important elements
to people’s history.
I believe that when communities become aware
of their history, they can turn this
into an economical benefit,
because this means social and cultural growth,
along with the possibility of investing in the future.
Overall, this has been a great and enriching experience,
especially after discussing with Dr. Murru.
I have left a link to the maps in the comments
with a bonus map of the Castello di Las Plassas
I hope you enjoyed the video and thanks for watching.