https://karstcampsite.com/
index - KARST CAMP SITE
indexkarstcampsite
https://geoparkea.eus/es/visitas-guiadas
Visitas guiadas - Geoparkea - Flysch & Karst experience
visitas guiadasgeoparkeaflyschkarstexperience
https://cavesofmalaysia.wordpress.com/
CAVES OF MALAYSIA – Caves, karst & limestone hills of Malaysia
caves of malaysiakarstlimestonehills
https://karstgoods.com/en-us/
Karst Goods | Home
We started Karst in 2016, in Sydney with an original idea and a genuine purpose.
karstgoods
https://nckri.org/wp-content/uploads/2021/01/53.html
Purchase Zithromax Canada - National Cave and Karst Research Institute
purchasezithromaxcanadanationalcave
https://karst.iah.org/
WELCOME - Commission on Karst Hydrogeology
Jul 16, 2026 - The Commision on Karst Hydrogeology, widely known as the Karst Commission is a part of The International Association of Hydrogeologists, a charitable...
welcomecommissionkarsthydrogeology
https://www.eurokarst.org/
Eurokarst 2026 – The bi-annual european Karst conference / Aug. 30 to Sep. 4
The bi-annual european Karst conference / Aug. 30 to Sep. 4
https://digitalcommons.usf.edu/caves_and_karst/62/
"Caves and Karst, Volume 12, No. 3, May/June 1970" by Arthur L. Lange
Content: Reviews -- A Possible Way of Tracing Groundwater Flows in Karst, Geophysical Prospecting -- From the Current Literature
https://digitalcommons.usf.edu/caves_and_karst/48/
"Caves and Karst, Volume 11, No. 2, March/April 1969" by Arthur L. Lange
Content: Quartzite Rubble and Bean-Ore Conglomerate: A Key Horizon in Cave Sediments
https://reforms-investments.ec.europa.eu/projects/modernization-institute-adriatic-crops-and-karst-reclamation-infrastructure-0_en
Modernization of the Institute for Adriatic Crops and Karst Reclamation infrastructure - Reforms...
The objective of this investment is to contribute to the development of sustainable tourism through the green and digital transition by implementing green...
of theinstitute for
https://digitalcommons.usf.edu/ijs/vol25/iss3/13/
"Gypsum karst in the United States" by Kenneth S. Johnson
Gypsum is one of the most soluble of common rocks; it is dissolved readily to form caves, sinkholes, disappearing streams, and other karst features that...
in the united statesgypsumkarstkennethjohnson
https://digitalcommons.usf.edu/ijs/vol24/iss1/3/
"Karst in siliceous rocks: the speleothem medium of finger flutings and" by Robert G. Bednarik
The isotopic geochemistry relating to the re-precipitation of calcite in caves is considered, in terms of its theory, natural manifestations, and relationship...
https://file.scirp.org/Html/10-6701943_34708.htm
SWAT Model Prediction of Phosphorus Loading in a South Carolina Karst Watershed with a Downstream...
https://www.nps.gov/ozar/learn/nature/caves.htm
Caves and Karst - Ozark National Scenic Riverways (U.S. National Park Service)
u scaveskarstozarknational
https://sma1wonosari.com/keunikan-formasi-batuan-karst-goa-purba-sebagai-destinasi-ekoturisme-lokal/
Keunikan Formasi Batuan Karst Goa Purba Sebagai Destinasi Ekoturisme Lokal - SMA NEGERI 1 WONOSARI
Jul 14, 2026 - keunikan formasi batuan karst di goa purba memberikan wawasan mendalam bagi siswa mengenai sejarah geologi
https://pure.lib.usf.edu/en/publications/application-of-a-karst-environmental-disturbance-index-in-hillsbo-2/
Application of a karst environmental disturbance index in Hillsborough County. - University of...
of ahillsborough countyapplicationkarstenvironmental
https://infoscience.epfl.ch/entities/publication/53d3328b-5b8d-4f83-96a0-095bef424e17
Possibilities and limits to predict the 3D geometry of karst systems within the inception horizon...
possibilities and limits
https://ucrisportal.univie.ac.at/en/publications/karst-features-initiated-by-the-uprooting-of-trees-during-storms-/
Karst Features initiated by the Uprooting of Trees during Storms, a Case Study - University of...
https://www.fieldtheory.us/caves-and-karst
Caves and Karst — FIELD THEORY
caveskarstfieldtheory
https://inside-dog.blogspot.com/2016/04/arc-review-dying-for-taste-by-leslie.html
Inside of a Dog: ARC Review: Dying for a Taste by Leslie Karst
Dying for a Taste Author: Leslie Karst Series: A Sally Solari Mystery Publication: Crooked Lane Books (April 12, 2016) Description: A...
inside of a dogarc review
https://www.metmuseum.org/art/collection/search?q=John+Karst&searchField=ArtistCulture
Results for "John Karst" - The Metropolitan Museum of Art
Search art at the Metropolitan Museum.
the metropolitan museumresultsjohnkarstart
https://harianjepara.id/sisi-lain-jepara-petualangan-caving-di-gua-karst-yang-menakjubkan/
Sisi Lain Jepara: Petualangan Caving di Gua Karst yang Menakjubkan - Harian Jepara
Apr 25, 2026 - mendunia atau pesona Kepulauan Karimunjawa, namun ada Sisi Lain Jepara yang jarang diketahui oleh publik, yakni potensi wisata bawah tanahnya
sisi lainjeparapetualangancaving
https://www.usf.edu/arts-sciences/departments/geosciences/news/2025/school-of-geosciences-professor-wins-kwi-karst-award.aspx
School of Geosciences Professor Wins KWI Karst Award
school of geosciencesprofessor winskwikarstaward
https://digitalcommons.usf.edu/kip_articles/7975/
"Dams and Reservoirs in Karst" by Philip E. van Beynen
By Philip E. van Beynen, Published on 01/01/11
dams and reservoirskarstphilipvan
https://experts.mcmaster.ca/scholarly-works/235487
The Physiography of the Castleguard Karst and...
Learn about the scholarly work entitled The Physiography of the Castleguard Karst and...
physiographykarst
https://digitalcommons.usf.edu/caves_and_karst/54/
"Caves and Karst, Volume 10, No. 1, January/February 1968" by Arthur L. Lange
Content: The Changing Geometry of Cave Structures Part I: The Constant Solution Gradient -- Proceedings -- From the Current Literature
https://klikbalangan.id/konservasi-ekosistem-karst-fungsi-gua-alam-penyimpanan-air-bersih/
Konservasi Ekosistem Karst Fungsi Gua Alam Penyimpanan Air Bersih - Klik Balangan
Jul 26, 2026 - Balangan menyimpan struktur geologi unik berupa jaringan gua alam yang berfungsi sebagai reservoir raksasa penyimpan air bersih
gua alamair bersihkonservasiekosistemkarst
https://www.nps.gov/subjects/caves/things-to-do-and-places-to-go.htm
Things to Do and Places to Go - Caves and Karst (U.S. National Park Service)
things to do
https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.667988/full
Frontiers | A Combined Morphological and Molecular Evolutionary Analysis of Karst-Environment...
The karst environment is characterized by low soil water content, periodic water deficiency, and poor nutrient availability, which provides an ideal natural ...
frontierscombined
https://www.sammlungen.hu-berlin.de/objekte/stichworte/6767/
Karst, Josef
karstjosef
https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1002198/full
Frontiers | The characterization of microbial communities and associations in karst tiankeng
The karst tiankeng is a special and grand negative terrain on the surface, that maintains a unique ecosystem. However, knowledge about bacterial and fungal c...
microbial communitiesfrontierscharacterization
https://www.usgs.gov/publications/gypsum-karst-problems-constructing-dams-usa
Gypsum-karst problems in constructing dams in the USA | U.S. Geological Survey
Gypsum is a highly soluble rock and is dissolved readily to form caves, sinkholes, disappearing streams, and other karst features that typically are also...
https://digitalcommons.usf.edu/caves_and_karst/49/
"Caves and Karst, Volume 11, No. 1, January/February 1969" by Arthur L. Lange
Content: Reviews -- Ozark Underground Laboratory -- Proceedings -- From the Current Literature
https://an.wikipedia.org/wiki/Karst
Karst - Biquipedia, a enciclopedia libre
karstbiquipediaenciclopedialibre
https://egusphere.copernicus.org/preprints/2025/egusphere-2025-3510/
EGUsphere - Soil stoichiometric characteristics and influencing factors in karst forests under...
eguspheresoilcharacteristics
https://snackbarkarst.nl/
Snackbar Karst - Home
snackbarkarst
https://digitalcommons.usf.edu/caves_and_karst/75/
"Caves and Karst, Volume 14, No. 5, September/October 1972" by Arthur L. Lange
Content: Control of Unwanted Plant Growth in Electrically Lighted Caves -- Notice to subscribers -- Erratum -- Reviews -- From the Current Literature -- From...
https://www.usgs.gov/publications/rift-related-volcanism-and-karst-geohydrology-southern-ozark-dome
Rift-related volcanism and karst geohydrology of the southern Ozark Dome | U.S. Geological Survey
This field trip examines the geology and geohydrology of a dissected part of the Salem Plateau in the Ozark Plateaus province of south-central Missouri. Rocks...
https://discovery.fiu.edu/display/pub100875
The Influence of Hydrologic Restoration on Groundwater-Surface Water Interactions in a Karst...
https://agris.fao.org/search/en/providers/122397/records/6851481253e52c13fc7612e9
Influence of a long-term storage in anaerobic conditions on Norway spruce (Picea abies, L. Karst.)...
https://www.mdpi.com/2073-4441/15/10/1823
Divergence in Quantifying ET with Independent Methods in a Primary Karst Forest under Complex...
A multi-technology study of evapotranspiration was conducted on the tropical seasonal forest in Nonggang Karst of Guangxi. From January 2019 to June 2020,...
https://cordis.europa.eu/project/id/40552/reporting/fr
Climate change impacts in a karst landscape of the Austrian Alps: effects on the soil resources |...
Latest report summary
https://www.cafepress.com/business/product-6058-design-503406
Karst 5.5"x8.5" Stone Journal | CafePress Business
Elevate your note-taking experience with this innovative, eco-conscious notebook crafted from recycled stone paper. Perfect for capturing creative ideas and...
stone journalkarstcafepressbusiness
https://digitalcommons.usf.edu/caves_and_karst/64/
"Caves and Karst, Volume 12, No. 5, September/October 1970" by Arthur L. Lange
Content: Discussion of "The Detection of Prehistoric Earthquakes from Fractured Cave Structures" -- Review -- From the Current Literature
https://digitalcommons.usf.edu/caves_and_karst/41/
"Caves and Karst, Volume 15, No. 3, May/June 1973" by Arthur L. Lange
Content: Replacement of Gypsum by Length-Slow Chalcedony in the Karst Subsurface -- Review -- From the World of Speleology -- From the Current Literature --...
https://www.earth.ox.ac.uk/environmental-proxies-karst-epik
Environmental Proxies in Karst (EPIK) | Department of Earth Sciences
department ofenvironmentalproxieskarstepik
https://www.in.gov/counties/monroe/Departments/parks-and-recreation/karst-farm-park-splash-pad/
Monroe County: Karst Farm Park Splash Pad
monroe countyfarm parkkarstsplashpad
https://budget.lis.virginia.gov/amendment/2020/1/SB30/Introduced/MR/373/1s/
373#1s (DCR) Karst Land and Water Resource Landowner Assistance. SB30 - Member Request
land and water
https://www.karlenekarst.com/
Welcome to Karlene Karst - Nutritionist, Author, TV Personality & Spokesperson
welcome totv personalitykarlenekarstnutritionist
https://uknowledge.uky.edu/kgs_mc/196/
"Mapped Karst Groundwater Basins in the Tell City and Part of the Jaspe" by Joseph A. Ray, Jack R....
By Joseph A. Ray, Jack R. Moody, Robert J. Blair, et al., Published on 01/01/09
https://www.karstdiving.com/
Karst Diving
karstdiving
https://se.copernicus.org/articles/7/457/2016/
SE - Delineating small karst watersheds based on digital elevation model and eco-hydrogeological...
https://wanderers-library.wikidot.com/karst
karst - The Wanderers' Library
A collection of extraordinary stories, hidden from ordinary eyes.
the wandererskarstlibrary
https://gis.data.mn.gov/datasets/minnesota-regions-prone-to-surface-karst-feature-development-1
Minnesota Regions Prone to Surface Karst Feature Development
Maps created using this product can be used as standalone products or can be used in conjunction with the Minnesota Karst Features Database for planning...
minnesotaregionspronesurfacekarst
https://www.energy.virginia.gov/geology/sinkholes.shtml
Virginia Energy - Geology and Mineral Resources - Sinkholes and Karst
geology and mineral resourcesvirginiaenergysinkholeskarst
https://www.geocaching.com/geocache/GCKY4B_harz-karst-landscape-earthcache
GCKY4B Harz Karst Landscape Earthcache (Earthcache) in Niedersachsen, Germany created by Team...
Geocaching is a treasure hunting game where you use a GPS to hide and seek containers with other participants in the activity. Geocaching.com is the listing...
in niedersachsencreated byharzkarstlandscape
https://www.uky.edu/KGS/gis/karst500k%20.htm
The Karst Occurrence GIS polygon coverages for Kentucky were compiled
karstoccurrencegispolygoncoverages
https://pure.lib.usf.edu/en/publications/sequence-of-secondary-phosphates-deposition-in-a-karst-environmen-2/
Sequence of Secondary Phosphates Deposition in a Karst Environment - University of South Florida
in a
https://www.karst-laos.com/
Accueil - Karst
accueilkarst
https://digitalcommons.usf.edu/kip_articles/2157/
"Geomorphology and hydrology of karst drainage basins and cave channel " by Victor R. Baker
Surface water in the karst drainage basins of east central New York is collected by swallow holes on upland surfaces. Free surface streams, flowing through...
https://www.usgs.gov/media/images/karst-working-group-sonora-caverns-texas
Karst Working Group: Sonora Caverns, Texas | U.S. Geological Survey
Inside the Edwards-Trinity Plateau aquifer, Sonora Caverns, Sonora, Texas.
working groupkarstsonoracavernstexas
https://www.usgs.gov/publications/effect-stream-size-attributes-estimating-fish-species-richness-a-karst-watershed
The effect of stream size attributes in estimating fish species richness in a karst watershed |...
No abstract available.
https://researchportalplus.anu.edu.au/en/publications/hominids-and-palaeoenvironments-in-the-moravian-karst-during-mari/fingerprints/
Hominids and palaeoenvironments in the Moravian Karst during Marine Isotope Stage 3: new...
https://portal.fis.tum.de/en/publications/mixed-norway-spruce-picea-abies-l-karst-and-european-beech-fagus-/
Mixed Norway spruce (Picea abies [L.] Karst) and European beech (Fagus sylvatica [L.]) stands under...
https://digitalcommons.usf.edu/kip_articles/2390/
"Hydrogeologic Controls on the Occurrence and Movement of Groundwater D" by National Cave and Karst...
By National Cave and Karst Research Institute, Published on 11/01/13
https://karst.legal/
Karst Legal
karstlegal
https://digitalcommons.usf.edu/caves_and_karst/56/
"Caves and Karst, Volume 9, No. 5, September/October 1967" by Arthur L. Lange
Content: Mixture-Solution Hollows in Worden's Cave, Iowa -- Review -- Annotated Bibliography
https://digitalcommons.usf.edu/kip_articles/4658/
"The role of dissolution kinetics in the development of karst aquifers " by W. Dreybrodt
To model the development of karst aquifers from primary fissures in limestone rock, a numerical model of solutional widening of such fractures by calcite...
the rolein development
https://www.prnewswire.com/news-releases/mesothelioma-compensation-center-now-recommends-attorney-erik-karst-of-karst-von-oiste-to-assist-an-electrician-or-electrical-worker-with-mesothelioma-nationwide----better-lawyers-better-compensation-results-300920518.html
Mesothelioma Compensation Center Now Recommends Attorney Erik Karst of Karst von Oiste to Assist an...
/PRNewswire/ -- The Mesothelioma Compensation Center says, "We have recommended attorney Erik Karst of the law firm of Karst von Oiste as the go to attorney...
https://digitalcommons.usf.edu/kip_articles/4309/
"Pleasant Valley Spring: A Newly Documented Karst Spring of the Texas H" by Brian B. Hunt, Brian A....
Texas Hill Country springs provide baseflow for rivers that recharge the downstream Edwards Aquifer. This study is an initial characterization of Pleasant...
https://mediasulawesi.com/mengenal-kampoeng-karst-rammang-keajaiban-alam/
Mengenal Kampoeng Karst Rammang Keajaiban alam
Mengenal Kampoeng Karst Rammang Rammang: Keajaiban Alam Sulawesi Selatan yang Mendunia Sulawesi Selatan menyimpan segudang pesona
mengenalkarstkeajaibanalam
https://asprtracie.hhs.gov/technical-resources/resource/12660/current-and-future-sinkhole-susceptibility-in-karst-and-pseudokarst-areas-of-the-conterminous-united-states
Current and Future Sinkhole Susceptibility in Karst and Pseudokarst Areas of the Conterminous...
Search the ASPR TRACIE Resource Library and view tailored Topic Collections comprised of current healthcare system preparedness resources.
current and future
https://cordis.europa.eu/project/id/40552/reporting/it
Climate change impacts in a karst landscape of the Austrian Alps: effects on the soil resources |...
Latest report summary
https://dealsharingaunt.blogspot.com/2026/04/murder-local-style-by-leslie-karst.html
Deal Sharing Aunt: MURDER, LOCAL STYLE by Leslie Karst Excerpt, Interview & Giveaway
MURDER, LOCAL STYLE by Leslie Karst April 13 - May 8, 2026 Virtual Book Tour Synopsis: An Orchid Isle Mystery Reti...
deal sharing aunt
https://scholars.cityu.edu.hk/en/publications/stability-and-repeatability-of-a-karst-like-hierarchical-porous-s/
Stability and Repeatability of a Karst-like Hierarchical Porous Silicon Oxide-Based Memristor -...
https://www.mdpi.com/2073-4441/15/4/726
Hydrogeochemical Characteristics and Evolution of Karst Groundwater in Heilongdong Spring Basin,...
Understanding the impact of natural processes and anthropogenic activities on geochemical evolution is vital for groundwater protection and utilization. This...
characteristicsevolution
https://www.in.gov/counties/monroe/Departments/parks-and-recreation/karst-disc-golf-course/
Monroe County: Karst Disc Golf Course
monroe countydisc golfkarstcourse
https://www.scirp.org/journal/articles?searchcode=Karst&searchfield=keyword&page=1
Karst - Articles - Scientific Research Publishing
scientific researchkarstarticlespublishing
https://digitalcommons.usf.edu/caves_and_karst/
Caves and Karst: Research in Speleology | Newsletters and Periodicals | University of South Florida
https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2021.795457/full
Frontiers | Multi-Step Combined Control Technology for Karst and Fissure Water Inrush Disaster...
Shield tunneling in highly fractured karst water-rich conditions easily result in water inrush disaster or even cause the karst caves' roof collapse. Severe ...
https://digitalcommons.usf.edu/kip_articles/2849/
"Journal of Cave and Karst Studies, Volume 68, No. 1, April 2006, Table" by National Speleological...
By National Speleological Society, Published on 04/01/06
https://eunis.eea.europa.eu/habitats/5319
EUNIS -Factsheet for Karst knapweed cliffs
Karst knapweed cliffs Cliff communities of the karst region of northeastern Italy, with the very rare Triestine endemic [Centaurea kartschiana], and with...
factsheetkarstknapweedcliffs
https://imgur.com/a/EsieF
Spartan 227 - Cassie Siren Karst - Album on Imgur
Discover topics like Awesome, and the magic of the internet at Imgur, a community powered entertainment destination. Lift your spirits with funny jokes,...
spartancassiesirenkarstalbum
https://pubchem.ncbi.nlm.nih.gov/taxonomy/Gehyra-girloorloo
Kimberley karst gecko | Taxonomy - PubChem
Taxonomy information for Gehyra girloorloo. Find diseases associated with this biological target and compounds tested against it in bioassay experiments.
kimberleykarstgeckotaxonomypubchem
https://carniolicum.blogspot.com/2019/06/a-week-in-notranjska-karst.html
Carniolicum - Wildlife & Biodiversity in Slovenia: A week in Notranjska & Karst
Another " Wild Slovenia in Spring " tour with Naturetrek is behind us. We've been helping co-leading this trip for the last two years now...
a weekwildlifebiodiversityslovenianotranjska
https://digitalcommons.usf.edu/kip_articles/6081/
"Groundwater vulnerability to pollution in karst aquifers, considering " by Ana I. Maria, Jose...
Groundwater vulnerability mapping is one of the tools most often applied to analyse the sensitivity of karst aquifers to pollution. These maps aim to support...
https://experts.arizona.edu/en/publications/a-piecewise-grey-system-model-for-study-the-effects-of-anthropoge/
A Piecewise Grey System Model for Study the Effects of Anthropogenic Activities on Karst...
https://pure.lib.usf.edu/en/publications/investigating-groundwater-vulnerability-of-a-karst-aquifer-in-tam-2/
Investigating Groundwater Vulnerability of a Karst Aquifer in Tampa Bay, Florida - University of...
tampa bay florida
https://www.lesliekarstauthor.com/
Leslie Karst Author
Leslie Karst is the author of JUSTICE IS SERVED, the Sally Solari Mystery Series, and Orchid Isle Mystery Series
leslie karstauthor
https://akmilaceh.id/identifikasi-jejak-kaki-di-medan-karst-pengembangan-teknik-intelijen-akmil-aceh/
Identifikasi Jejak Kaki di Medan Karst: Pengembangan Teknik Intelijen AKMIL Aceh - AKADEMI MILITER...
Jul 5, 2026 - Teknik identifikasi jejak kaki di medan karst menjadi keahlian khusus yang dikembangkan oleh AKMIL Aceh untuk mendukung efektivitas.
https://spigunungkidul.com/pelaksanaan-simulasi-bencana-gempa-dan-longsor-pada-sekolah-karst/
Pelaksanaan Simulasi Bencana Gempa Dan Longsor Pada Sekolah Karst - SERIKAT PETANI INDONESIA GUNUNG...
Jul 21, 2026 - Simulasi bencana gempa bumi dan tanah longsor yang diselenggarakan secara berkala di kawasan sekolah wilayah bentang alam karst
https://pure.lib.usf.edu/en/publications/hydrological-controls-on-transient-aquifer-storage-in-a-karst-wat/
Hydrological Controls on Transient Aquifer Storage in a Karst Watershed - University of South...
https://www.mdpi.com/2072-4292/13/17/3368
Using Field Spectroradiometer to Estimate the Leaf N/P Ratio of Mixed Forest in a Karst Area of...
The ratio between nitrogen and phosphorus (N/P) in plant leaves has been widely used to assess the availability of nutrients. However, it is challenging to...
https://www.belizekarst.org/
Belize Karst Habitat Conservation | Belize NGO
Sep 29, 2025 - Belize Karst Habitat Conservation is a registered NGO established with the purpose of developing and managing Tapir Mountain Nature Reserve, focusing on...
habitat conservationbelizekarstngo
https://home.nps.gov/subjects/caves/speleothems.htm
Speleothems - Caves and Karst (U.S. National Park Service)
u snational parkcaveskarstservice
https://www.nps.gov/subjects/caves/karst-landscapes.htm
Karst Landscapes - Caves and Karst (U.S. National Park Service)
u snational parkkarstlandscapescaves
https://gc.copernicus.org/articles/4/329/2021/gc-4-329-2021-metrics.html
GC - Metrics - Development and implementation of virtual field teaching resources: two karst...
Abstract. During the summer of 2020, many geology field camps were canceled due to the COVID-19 pandemic, including the karst geomorphology field course I was...
https://cordis.europa.eu/project/id/101027303
KArstic submarine fReshwater Springs | KARST | Project | Fact Sheet | H2020 | CORDIS | European...
Submarine groundwater discharge (SGD) is the flow of fresh or recirculated groundwater into the ocean. This process introduces substantial amounts of nutrients...
project fact sheetsubmarinefreshwaterspringskarst
https://www.mdpi.com/2073-4441/6/9/2782
Characteristics of Point Recharge in Karst Aquifers
Karstic groundwater basins are characterized by both point and diffuse recharge. This paper describes the hydrologic characteristics of point recharge and...
characteristicspointrechargekarstaquifers
https://hess.copernicus.org/articles/19/137/2015/hess-19-137-2015-metrics.html
HESS - Metrics - Thermal damping and retardation in karst conduits
hessmetricsthermaldampingretardation