. Smithsonian miscellaneous collections . g material along the shoreline. The change in conditions from those prevalent on winter beaches tothose prevalent on summer beaches is not a gradual one. The changeoccurs over a very small range of steepness values, with a criticalHo/Lo value (wave height/wave length) equal to approximately transport along the shoreline occurs when this value liesbetween and Calculations for waves approaching SableIsland yield an average Ho/Lo value of for winter waves for summer waves. 28 SMITHSONIAN MISCELLANEOUS COLLECTIONS V
. Smithsonian miscellaneous collections . g material along the shoreline. The change in conditions from those prevalent on winter beaches tothose prevalent on summer beaches is not a gradual one. The changeoccurs over a very small range of steepness values, with a criticalHo/Lo value (wave height/wave length) equal to approximately transport along the shoreline occurs when this value liesbetween and Calculations for waves approaching SableIsland yield an average Ho/Lo value of for winter waves for summer waves. 28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 It appears that on Sable Island beaches maximum transport shouldtake place along the forebeach zone of the south beach during thespring and summer months, while sand is eroded from the north beachduring winter. This conclusion is supported by the steeper bottomgradient, indicative of erosion, seaward of the north beach, comparedto the gentle gradient off the south beach (James and Stanley, inpress). SABLE ISLAND MAPS 1 767 - 1964. Fig. 18.—The evolution of Sable Island based on data summarized from surveysand charts dating from 1766 (after Cameron, 1965). SEDIMENT MOVEMENT Erosion of sediment from the north and addition of sediment to thesouth is contributing to the arcuate shape of Sable Island. Althoughdunes are breached during winter, sand added by summer winds fromthe southwest (see plate 2, fig. 2) prevents their complete are two possible sources for south beach sand : (a) sand blownto the open ocean from blowouts during winter, (b) bottom sedimenttransported landward by long waves or surf beat from the open oceanto the south. NO. 7 SEDIMENT TRANSPORT, SABLE ISLAND JAMES & STANLEY 20, Our study suggests that Sable Island is not destined to be erodedand disappear as indicated in most earlier works. Storms cause con-siderable modification of the islands periphery and morphology, andchanges in the length, shape, and orientation of the terminal bars
Size: 1542px × 1620px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, bookidsmiths, booksubjectscience
