Abstract
The area is a complex of highland plateaus, uplands, and lowlands representing Tertiary planation levels; one surface is a paleoplain with largely inherited glacial relief, which has been exhumed from Cambrian cover strata. Straddling the Appalachian! Shield margin, the area records the interplay of two ice domains - the Newfoundland ice cap complex and the Laurentide Ice Sheet. Glacial terrains of different geomorphic maturity are attributed to three main glaciations. The oldest (St. John Zone) records a maximal Laurentide invasion; from relative stream entrenchment, it maybe 400-500 ka (oxygen isotope stage 12). The intermediate-age terrain or Doctors Zone may be stage 6 (Illinoian). It shows that ice from the Canadian Shield merged with local ice, but left nunataks above 590 m; on Grey Islands, local glaciers occupied cirques that are now submerged 40 m. The last main glaciation (Long Range Zone) is dated to Late Wisconsinan time by marine deposits. Crosscutting ice flow features define six phases. First, Shield ice crossed Strait of Belle Isle, overran White Hills, and merged with Newfoundland ice below 500 m along an interlobate moraine near the head of Esquiman Channel. Retreat by calving in deglacial Goldthwait Sea produced 400 De Geer moraines. Glaciers stabilized by 12.6 ka: Long Range ice built the Piedmont Moraines, while Shield ice built the Bradore and Belles Amours moraines at the 150 m marine limit. When the Polar Front shifted, causing a climatic reversal, Long Range ice readvanced and built the Ten Mile Lake Moraine at 11 ka. The resulting gravitational marine stillstand cut a rock platform (Bay of Islands Surface). A fossil cliff near tide level records a late Holocene transgression; emergence is now slow or complete. Sporadic ice wedges and palsas are relict from the Little Ice Age, but solifluction and nivation continue above 400 m; cryoturbation is active at sea level. Faulted glacial pavements suggest neotectonic stress release.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
