. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. 178 Figure 45. Canton Island, showing water sample sites meters 500 0 1000 certainly the work of seawater flowing onto, across, or between ancient islands. The flats are morphologically similar to those described on Fanning Atoll by Guinther (1971) and on Diego Garcia Atoll by Stoddart and Taylor (1971), but the Canton flats differ in not having a regular tidal flow of lagoon water. Evidence for a higher stand of sea level at Canton (either eustatic or tectonic) may be found in the extensive escarpment o
. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. 178 Figure 45. Canton Island, showing water sample sites meters 500 0 1000 certainly the work of seawater flowing onto, across, or between ancient islands. The flats are morphologically similar to those described on Fanning Atoll by Guinther (1971) and on Diego Garcia Atoll by Stoddart and Taylor (1971), but the Canton flats differ in not having a regular tidal flow of lagoon water. Evidence for a higher stand of sea level at Canton (either eustatic or tectonic) may be found in the extensive escarpment of detrital limestone surrounding the lagoon and bordering portions of the inland flats. The vertical relief of the limestone exceeds 2 m in some places. A consequence of the subsequent lowering of relative sea level was to strand the intertidally or sub- tidally formed flats above the present influence of tidal water. The possibility of present-day seawater incursion onto the flats during the seasonal higher level of the sea at Canton seems unlikely. Our visit coincided with the month of maximum average sea level (December), yet the flats were above any tide level. Nonetheless, particularly large positive deviations in sea level, associated with strong equatorial countercurrent transport (Wyrtki, 1973), might allow occasional tidal flow across the flats. Therefore, formation of these flats at present sea levels cannot be ruled out. Active tidal flats with well-delimited tidal channels are restricted to one large inlet at the extreme southeast end of the lagoon (stations 26, 27, 30, and 31 in Fig. 46) and to several smaller areas separated from the lagoon by sandbars. The stranded inland flats slope gently toward more or less central dry channels whose courses are eventually lagoonward. These channels apparently connect the inland flats to the lagoon, although the present lagoon beach is not broken where the channels contact the shore. Despite the lack of direct evidence indi- c
Size: 1587px × 1574px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauth, bookauthorsmithsonianinstitutionpress, bookcentury1900
