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Figure 1. (A) Disassembly view of the “Print Your Compass” (PYC) 3D models. (B) Field picture showing the outcrop on which the PYC compass was tested.
The outcrop displays an augen orthogneiss massif with foliations slightly dipping to the NNW, itself crosscut by late joints and faulted structures. Lower
left is a sketch map of the French basement in blue locating the French Massif Central and the investigated outcrop (yellow star). (C) Two columns of
comparative Stereonet plots. The first column shows measurement of the subvertical joints and faults, the second shows the measurement of foliations.
Poles of planes are shown with the average value as a blank square. Rose diagrams show the distribution of strikes’ azimuths. These plots were done
using the Geolokit app (Triantafyllou et al., 2017).

collapse (e.g., Gardien et al., 2021). These strike direction trends to N339.6 ± 1.5°, and REFERENCES CITED
ductile structures are crosscut by recent the mean dipping value is 89.9° to the E. Allmendinger, R.W., Siron, C.R., and Scott, C.P.,
subvertical joints and faults. Tests were The PYC compass provides a mean strike 2017, Structural data collection with mobile de-
made on these two types of structures with direction at N341.9 ± 1.7° and an averaged vices: Accuracy, redundancy, and best practices:
twenty planar measurements for each com- dipping value at 86.1° to the E (see Fig. 1C). Journal of Structural Geology, v. 102, p. 98–112,
https://doi.org/10.1016/j.jsg.2017.07.011.
pass: (i) Concerning foliation measure- The reliability of the PYC compass is de Lamotte, D.F., Leturmy, P., Souloumiac, P., and
ments, using the FieldMove digital com- attested first by the small polar differences de Lamotte, A.F., 2020, Using 3D printed models
pass, the mean strike direction is N229.0 ± between PYC mean pole values and those to help the understanding of geological maps:
6.6° (95% polar confidence), and the mean measured with the Topochaix and the Copernicus Meetings, no. EGU2020-8757.
dipping value is 22.2° to the NW. For the FieldMove Clino app, which yields 4.4° Gardien, V., Martelat, J.E., Leloup, P.H., Mahéo, G.,
Topochaix Universelle compass, the mean and 2.5°, respectively, for the foliation Bevillard, B., Allemand, P., and Fellah, C., 2021,
strike direction is N231.3 ± 5.0°, and the structures and 0.2° and 15.0°, respectively, Fast exhumation rate during late orogenic exten-
mean dip is at 20.9° to the NW. For the PYC for the joint/faulted structures; and second sion: The new timing of the Pilat detachment fault
(French Massif Central, Variscan belt): Gondwana
printed compass, the mean strike direction by the small radius of polar confidence at Research, https://doi.org/10.1016/j.gr.2021.10.007.
is at N232.7 ± 4.9° and the averaged dip- 5% of 2.35°, indicating a reduced data Hasiuk, F., 2014, Making things geological: 3-D print-
ping value was 20.7° to the NW with a spread and a good reproducibility during ing in the geosciences: GSA Today, v. 24, no. 8,
radius of polar confidence at 5% of 2.35° p. 28–29, https://doi.org/10.1130/GSATG211GW.1.
(Fig. 1C). (ii) Concerning the subvertical structures measurement. Lundmark, A.M., Augland, L.E., and Jørgensen,
joints and faults measurements, the S.V., 2020, Digital fieldwork with Fieldmove—
How do digital tools influence geoscience stu-
FieldMove digital compass provides an ACKNOWLEDGMENTS dents’ learning experience in the field?: Journal of
The author acknowledges support from the Uni-
averaged strike direction of N344.2 ± 2.7° versité Claude Bernard de Lyon and the LGLTPE Geography in Higher Education, v. 44, no. 3,
and a mean dip at 87.2° to the E. For the laboratory for the grant: “Bonus Qualité Recher- p. 427–440, https://doi.org/10.1080/ 03098265.2020
Topochaix Universelle compass, the mean che–EC 2021.” .1712685.

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