Editing Shadow marks (section)

{{short description|Shadows on the ground that indicate buried archaeological structures.}}
{{Infobox
| title            = Shadow marks
| image            = [[File:Aerial photograph of Maiden Castle from the west, 1937.jpg|250px|alt=Aerial view of Maiden Castle showing shadow marks]]
| caption          = Aerial view showing shadow marks over Maiden Castle hillfort
| label1           = Type
| data1            = Archaeological surface feature
| label2           = Visibility conditions
| data2            = Low sun angle (morning or afternoon), clear skies
| label3           = Detection methods
| data3            = Aerial photography, multispectral imaging, SAR, LiDAR
| label4           = Related techniques
| data4            = Crop marks, soil marks, NDVI, GPR
}}
'''Shadow marks''' are surface patterns formed when low-angle sunlight casts elongated shadows across slight variations in ground elevation, revealing buried or [[eroded]] features otherwise invisible at ground level. <ref name=":0">{{Cite journal |last=Stefano |first=Campana |date=2016 |title=Archaeology, remote sensing |url=https://d1wqtxts1xzle7.cloudfront.net/49462117/Enciclopedia_GeoArchaeoloy_Springer_MENABO_low_res-libre.pdf?1475970604=&response-content-disposition=inline%3B+filename%3DArchaeology_Remote_Sensing_Encyclopedia.pdf&Expires=1746686598&Signature=Wyw0vxrekpWa0xHtrM0iaZZNo0ShI~rVMiqytKzurQfMhO1n1nxD7e1ZbUgMRQsjncwoiGFyTJlzaytCJ9u9ab~MhJGkazldEdaoFQDQy-XsFVwU5J3~YwLEDSK5DwngKbFRmQBZbVUEAnNCAAIoYlgyU-rZkxr3zgtI-VNKnKrQ8VddbcbhpcYDMF8Pnwhee-VyofgsI4hu8oxXVM4eJp-p0KG9k7XoyGLf1cH8tJdrxD0Yg1juN1P0gWM9VN70QyRGqR7qBHVzIjiugXlyX~Nrqu9lRbo2fn5ejqRprO1rQpX21u8V2T4wHx4ArQ9dD7xKt0opYS~Edcer5NEJdQ__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA |journal=Encyclopedia of Geoarchaeology |series=Dordrecht/Heidelberg/New York/London: Springer (2016) |pages=5–6}}</ref> Commonly observed through [[aerial photography]] or [[satellite imagery]], shadow marks assist archaeologists in identifying ancient structures, [[Earthworks (archaeology)|earthworks]], and landscape modifications.<ref name=":5">{{Cite journal |last1=Chen |first1=Fulong |last2=Masini |first2=Nicola |last3=Yang |first3=Ruixia |last4=Milillo |first4=Pietro |last5=Feng |first5=Dexian |last6=Lasaponara |first6=Rosa |date=2014-12-23 |title=A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data |journal=Remote Sensing |language=en |volume=7 |issue=1 |pages=27 |doi=10.3390/rs70100024 |doi-access=free |bibcode=2014RemS....7...24C |issn=2072-4292}}</ref> Their visibility depends on lighting angle, [[surface reflectance]] ([[albedo]]), and environmental conditions such as vegetation or cloud cover.<ref name=":6">{{Cite journal |last1=Watteeuw |first1=Lieve |last2=Hameeuw |first2=Hendrik |last3=Vandermeulen |first3=Bruno |last4=Van der Perre |first4=Athena |last5=Boschloos |first5=Vanessa |last6=Delvaux |first6=Luc |last7=Proesmans |first7=Marc |last8=Van Bos |first8=Marina |last9=Van Gool |first9=Luc |date=November 2016 |title=Light, shadows and surface characteristics: the multispectral Portable Light Dome |url=http://link.springer.com/10.1007/s00339-016-0499-4 |journal=Applied Physics A |language=en |volume=122 |issue=11 |page=976 |doi=10.1007/s00339-016-0499-4 |bibcode=2016ApPhA.122..976W |issn=0947-8396}}</ref> Shadow marks differ from crop or soil marks in that they rely on topographic contrast rather than biological or chemical changes.<ref name=":3">{{Cite web |title=Crop Marks and Soil Marks |url=https://www.metaldetectingworld.com/metaldetecting_research_p61.shtml |access-date=2025-05-08 |website=www.metaldetectingworld.com}}</ref><ref name=":2">{{Cite journal |last1=Chen |first1=Fulong |last2=Masini |first2=Nicola |last3=Yang |first3=Ruixia |last4=Milillo |first4=Pietro |last5=Feng |first5=Dexian |last6=Lasaponara |first6=Rosa |date=2014-12-23 |title=A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data |journal=Remote Sensing |language=en |volume=7 |issue=1 |pages=30–37 |doi=10.3390/rs70100024 |doi-access=free |bibcode=2014RemS....7...24C |issn=2072-4292}}</ref> Modern [[remote sensing]] techniques—such as [[Lidar|LiDAR]], [[Normalized difference vegetation index|NDVI]], and [[Synthetic-aperture radar|Synthetic Aperture Radar]] (SAR)—are often integrated with shadow mark analysis to improve accuracy and overcome environmental limitations.<ref name=":8">{{Cite journal |last=Stefano |first=Campana |date=2016 |title=Archaeology, remote sensing |url=https://d1wqtxts1xzle7.cloudfront.net/49462117/Enciclopedia_GeoArchaeoloy_Springer_MENABO_low_res-libre.pdf?1475970604=&response-content-disposition=inline%3B+filename%3DArchaeology_Remote_Sensing_Encyclopedia.pdf&Expires=1746686598&Signature=Wyw0vxrekpWa0xHtrM0iaZZNo0ShI~rVMiqytKzurQfMhO1n1nxD7e1ZbUgMRQsjncwoiGFyTJlzaytCJ9u9ab~MhJGkazldEdaoFQDQy-XsFVwU5J3~YwLEDSK5DwngKbFRmQBZbVUEAnNCAAIoYlgyU-rZkxr3zgtI-VNKnKrQ8VddbcbhpcYDMF8Pnwhee-VyofgsI4hu8oxXVM4eJp-p0KG9k7XoyGLf1cH8tJdrxD0Yg1juN1P0gWM9VN70QyRGqR7qBHVzIjiugXlyX~Nrqu9lRbo2fn5ejqRprO1rQpX21u8V2T4wHx4ArQ9dD7xKt0opYS~Edcer5NEJdQ__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA |journal=Encyclopedia of Geoarchaeology |series=Dordrecht/Heidelberg/New York/London: Springer (2016) |pages=6–19}}</ref><ref name=":1">{{Citation |last1=Masini |first1=Nicola |title=Sensing the Past from Space: Approaches to Site Detection |date=2017 |work=Sensing the Past: From artifact to historical site |pages=23–60 |editor-last=Masini |editor-first=Nicola |url=https://link.springer.com/chapter/10.1007/978-3-319-50518-3_2 |access-date=2025-05-08 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-50518-3_2 |isbn=978-3-319-50518-3 |last2=Lasaponara |first2=Rosa |editor2-last=Soldovieri |editor2-first=Francesco}}</ref><ref name=":15">{{Cite journal |last1=Chen |first1=Fulong |last2=Masini |first2=Nicola |last3=Yang |first3=Ruixia |last4=Milillo |first4=Pietro |last5=Feng |first5=Dexian |last6=Lasaponara |first6=Rosa |date=2014-12-23 |title=A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data |journal=Remote Sensing |language=en |volume=7 |issue=1 |pages=24–50 |doi=10.3390/rs70100024 |doi-access=free |bibcode=2014RemS....7...24C |issn=2072-4292}}</ref> Recent developments also include AI-assisted image classification and virtual light simulations to enhance detection.<ref name=":13">{{Cite journal |last1=Luo |first1=Lei |last2=Wang |first2=Xinyuan |last3=Guo |first3=Huadong |date=2024-07-01 |title=Transitioning from remote sensing archaeology to space archaeology: Towards a paradigm shift |url=https://www.sciencedirect.com/science/article/abs/pii/S0034425724002189 |journal=Remote Sensing of Environment |volume=308 |pages=4–15 |doi=10.1016/j.rse.2024.114200 |bibcode=2024RSEnv.30814200L |issn=0034-4257}}</ref> Beyond [[archaeology]], shadow marks are applied in [[geomorphology]], [[heritage conservation]], and [[battlefield]] studies, and continue to be a key proxy in multi-sensor approaches to landscape interpretation.<ref name=":0" />