Editing Gully (section)

== Artificial gullies ==
Gullies can be formed or enlarged by several human activities.

Artificial gullies are formed during [[hydraulic mining]] when jets or streams of water are projected onto soft [[alluvial deposits]] to extract [[gold]] or [[tin ore]]. The remains of such mining methods are very visible landform features in old [[gold mining|goldfield]]s such as in [[California]] and northern Spain. The [[badland]]s at [[Las Medulas]], for example, was created during the Roman period by [[hushing]] or [[hydraulic mining]] of the gold-rich alluvium with water supplied by numerous aqueducts tapping nearby rivers.<ref>{{Cite journal |last1=Razavi-Termeh |first1=Seyed Vahid |last2=Sadeghi-Niaraki |first2=Abolghasem |last3=Choi |first3=Soo-Mi |date=2020-01-01 |title=Gully erosion susceptibility mapping using artificial intelligence and statistical models |journal=Geomatics, Natural Hazards and Risk |language=en |volume=11 |issue=1 |pages=821–844 |doi=10.1080/19475705.2020.1753824 |bibcode=2020GNHR...11..821R |s2cid=219070139 |issn=1947-5705|doi-access=free }}</ref> Each [[Aqueduct (watercourse)|aqueduct]] produced large gullies below by erosion of the soft deposits. The effluvium was carefully washed with smaller streams of water to extract the [[Gold nugget|nuggets]] and gold dust.{{citation needed|date=October 2011}}