## 2 Materials and Methods  
We selected an archaeological area that was affected by a recent fire. The studied area is El Berrueco, in the border of the regions of Avila and Salamanca (Spain). This place underwent a fire in 2017, which was active for two days. The area includes several archaeological sites, where six neolithic locations were affected during the fire. This study focused in the largest of all of them (Los Tejares). The methodology combined in situ measurements in outcrops of the area affected by the fire with laboratory tests of samples taken from the site in which the effect of high temperatures was simulated in an oven in controlled conditions.  
The in-situ tests consisted of measurements at the archaeological site using the magnetic susceptometer KT-10 Terraplus. This instrument allows for measuring magnetic susceptibility rapidly and with high sensitivity. Seven locations were measured with 10 to 20 measures in each one. In addition, a block of the outcropping rock was taken for the laboratory tests from a close-by area not affected by the fire. The block was cut in 4 cm cubes. Then, 18 cubes were selected, three of them were left as blank samples and 15 were chosen for heating tests in a SNOL 30/1300 oven.  
Samples were dried at 40 \({}^{\circ}\)C until constant weight was ensured and then introduced in the oven for heating, choosing three samples for each target temperature. Five different target temperatures were chosen (200 \({}^{\circ}\)C, 400 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, 800 \({}^{\circ}\)C, and 1000 \({}^{\circ}\)C) to recreate the high temperatures produced by fires. This process consisted in three phases: a heating phase to the target temperature, a three-hour isotherm stage and finally a free-cooling phase back to room temperature within the oven. The cubes were again weighed after heating and measured with the susceptometer, one measure per side (and therefore six measures per cube).  
Later, the 4 cm cubes were cut into eight smaller cubes of 2 cm cubes to be analysed with a KLY-4 Kappabridge Pick-up Unit along with CS-3 Temperature Control Unit (AGICO Inc. Brno, Czech Republic), to obtain data about the magnetic properties such as the magnetic susceptibility and the variation in the magnetic susceptibility (\(k\)) with the temperature (T). These analyses are destructive and therefore, unsuitable for a heritage context, but were used to evaluate the field results obtained with the KT-10 susceptometer. Some cubes were grinded and used to measure the variation in the magnetic susceptibility with the temperature using the KLY4-CS3 and to measure different magnetic parameters in the Ultra-sensitive field translation balance (Petersen Instruments, Mag-Instruments, Munich, Germany) or \"Curie balance\". This instrument allows to obtain the hysteresis cycles and the variation in the induced magnetization with the temperature, with a 36.7 mT external field. The hysteresis cycles are plotted using the programme RockMag Analyzer ([PERSON]) VFTBAnalyzer 2.0. The KLY-4 Kappabridge measures are performed using a 0.367 mT external field. These tests permit to determine the presence of ferromagnetic minerals due to the drop of the \(k\) value or the induced magnetization of the sample, which are diagnostic for each ferromagnetic mineral [22]. Furthermore, the presence of paramagnetic minerals can be deducted because, at low temperatures, the magnetic susceptibility graphs have a hyperbolic curve in the \(k\)-T analysis [21; 23; 24].