Rangarira ndima iri pasi apa uye ipapo pindura mubvunzo gare gare mumutauro mumwe chetewo sechikamu:  Passage: Yakapararira zvakanyanya kuchamhembe-kumaodzanyemba kumahombekombe ekumabvazuva kweRwizi rweHooghly, Kolkata iri mukati meGanges Delta yekumabvazuva kweIndia ingangoita 75 km (47 mi) kumadokero kwemuganhu wepasi rose neBangladesh; kukwirira kweguta kuri 1.5<unk>9 m (5<unk>30 ft). Zvikamu zvikuru zveguta racho pakutanga zvakanga zviri nzvimbo ine mvura yakanyoroveswa mumakumi emakore kuti vagare vanhu vakawanda. Nzvimbo dzakasara dzisina kugadziridzwa, dzinozivikanwa seEast Kolkata Wetlands, dzakatarwa se"nzvimbo ine mvura yakakosha yepasi rose" neRamsar Convention (1975). Sezvakaita nechikamu chikuru cheMupata weIndo-Gangetic, ivhu nemvura zvinonyanya kubva mumvura. Kolkata iri pamusoro pe"Bengal basin", inonzi pericratonic tertiary basin. Bheseni reBengal rine zvikamu zvitatu zvinoti: sherefu kana kuti chikuva chiri kumadokero; nzvimbo iri nechepakati kana kuti sherefu kana kuti nzvimbo yakatsvedza; uye nzvimbo yakadzika iri kumabvazuva uye kumaodzanyemba kwakadziva kumabvazuva. Kolkata iri pamusoro pechikamu chekumadokero kwenzvimbo ye hinge iyo ingangoita 25 km (16 mi) yakafara pakadzika ingangoita 45,000 m (148,000 ft) pasi pevhu. Zvikamu zvesherefu nezvisungo zvine zvikanganiso zvakawanda, pakati pazvo zvimwe zviri kushanda. Ukobvu hwese hwemadhaka ari pasi peKolkata hunosvika 7,500 m (24,600 ft) pamusoro penzvimbo yekristaro; yeiyi yepamusoro 350<unk>450 m (1,150<unk>1,480 ft) ndeye Quaternary, ichiteverwa ne4,500<unk>5,500 m (14,760<unk>18,040 ft) yeTertiary sediments, 500<unk>700 m (1,640<unk>2,300 ft) yekutsvaira kwekutsvaira kweCretaceous uye 600<unk>800 m (1,970<unk>2,620 ft) Permian-Carboniferous Gondwana matombo. Matombo equaternary anoumbwa nevhu, madhaka, uye marudzi akasiyana-siyana ejecha negwere. Iyi midzi yakaiswa pakati pemibhedha miviri yevhu: yakaderera pakadzika 250<unk>650 m (820<unk>2,130 ft); yepamusoro 10<unk>40 m (30<unk>130 ft) mukukora. Maererano neBureau of Indian Standards, pamwero unobva paI kusvika paV kuti uwedzere kukanganiswa nokudengenyeka kwepasi, guta racho riri mukati mechikamu chechitatu chechisimba.  Mubvunzo: Guta racho riri munharaunda ipi?
nzvimbo inodengenyeka III