. The Earth beneath the sea : History . Pleistocene periglacial deposits ^ ^ V V , Bed-rock ^ ^ X X X X ^ y-^^- Pleistocene ^^ Y. X ^ Bed-rock y y iVIuddy sand periglociol deposits X X X Y V V V Fig. 2. Diagram showing parts and section of a small estviary in Brittany. The marshes are fed by large tidal creeks (Dutch: geulen) meandering into the slikke, and smaller creeks (Dutch: prielen) dissecting the schorre. Straight sections are rare, and very pronounced meanders are much more common than in ordinary rivers, but their general evolution is the same, consisting of cut-offs, captures, etc. I
. The Earth beneath the sea : History . Pleistocene periglacial deposits ^ ^ V V , Bed-rock ^ ^ X X X X ^ y-^^- Pleistocene ^^ Y. X ^ Bed-rock y y iVIuddy sand periglociol deposits X X X Y V V V Fig. 2. Diagram showing parts and section of a small estviary in Brittany. The marshes are fed by large tidal creeks (Dutch: geulen) meandering into the slikke, and smaller creeks (Dutch: prielen) dissecting the schorre. Straight sections are rare, and very pronounced meanders are much more common than in ordinary rivers, but their general evolution is the same, consisting of cut-offs, captures, etc. Interconnections between creeks are frequent. The ebb current is more important in creek evolution than the flood current, since the former flows during a longer time than the latter. But on many slikkes in watts or estuaries, the channels show an inter-digitated pattern: some of them are flood channels which gradually shoal as they enter the watt, whereas others are only followed by the ebb current: these are deepest in their inner parts and gradually merge into shallow banks at their outer reaches. Such ebb- and flood-channels in the Scheldt estuary have been described by Van Veen (in Waddensymposium, 1950), and on several tidal flats around Great Britain by Robinson (1956), and elsewhere. The surface of the high marsh between the creeks includes ponds which are devoid of plants and are known as salt pans, in which the water becomes highly saline at neap tides by evaporation, a fact which may account for the absence of vegetation. Salt pans are often remnants of silted-up creeks, although some of them may have other origins. In the intertropical belt, grass is generally replaced by mangrove in tidal
Size: 4562px × 1096px
Photo credit: © The Bookworm Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectoceanbottom
