Documents found
-
541.More information
ABSTRACTThe Matane coastal area was deglaciated around 13 ka and submerged by the Goldthwait Sea. The area submerged was up to 3-4 km from the present coastline. The Appalachian ice front remained stationary for a while along the highland margin, a few kilometres only from the present shoreline. Because the sea was in contact with the ice front, there is no remaining shoreline of the initial phase of the postglacial submergence. The observed maximum altitude of the Goldthwait Sea is approximately 105 m, but it is most likely around 110 m. A wide delta plain was built between 13 to 12 ka at the mouth of the Matane River. The higher surface is, however, only 80 m in altitude. Ice-contact fluvioglacial terraces occurring on both sides of the Matane River valley indicate that the depression was filled by an ice tongue which retreated to the south and delayed the marine invasion within the valley. In the coastal area, flights of raised beaches, spread between 65 and 25 m in altitude and dated 11-9.5 ka, occur in the vicinity of Matane. The 15-m terrace emerged prior to 8 ka. Between 7 and 5 ka, the relative sea level (RSL) was at least similar to the present day level and most likely a few metres lower than the geodetic zero. Between 5 and 4 ka RSL rose again (Laurentian transgression) and was lowered subsequently to the present day level. A minor RSL fluctuation (1-2 m) occurred around 3 ka and, during subsequent emergence, built the Mitis terrace (beaches); this event is dated about 2 ka. According to tide gauge data for the period 1970-1980 at the Ste-Anne-des-Monts station, the shoreline is probably emerging at a mean annual rate of 2.2 mm or is possibly submerged at a mean annual rate of 0.55 mm. Presently shore erosion occurs almost everywhere in the Matane area and the delta front retreated many metres between 1950-1965.
-
542.
-
544.
-
548.
-
550.