Because of the scenario of rock samples non probability sampling methods are more likely preferable than probability methods. These include purposive, quota and convenience sampling methods.

See these links:

https://openei.org/wiki/Rock_Sampling

https://www.epa.gov/sites/default/files/2015-06/documents/marssim_chapter7.pdf

Please look at the following below links which may help you in your analysis:

https://openei.org/wiki/Rock_Sampling

https://pubs.usgs.gov/circ/1976/0735/report.pdf

https://link.springer.com/content/pdf/10.1007%2F0-387-30844-X_97.pdf

Thanks

Thanks

These are wells, trenches, excavation and tunnels. These methods need to applied according to the soil types