Since the Last Glacial Maximum (LGM), sea levels along the British Columbia coast have fluctuated markedly due to neotectonics, eustatic sea level changes, and isostatic depression and rebound. At the LGM, the Cordilleran Ice Sheet depressed the crust over which it formed, and created a raised forebulge along peripheral areas offshore. Under the ice, crustal depression resulted in sea levels about 200 m higher than present in southwest BC and eastern Vancouver Island; in contrast, sea levels in Haida Gwaii along the north coast were up to 150 m lower than today, due largely to the forebulge raising the land relative to the sea. Knowledge of sea level history on BC’s central coast however, is lacking.
I am working with colleagues to determine the postglacial relative sea level histories at a couple of sites on the British Columbia coast, including at Calvert Island on the central coast and Naikoon, Queen Charlotte Islands on the north coast. We are using LiDAR, optical luminescence and radiocarbon dating, and field mapping of glacial stratigraphy and raised shorelines in an effort to determine (1) the character of glaciation, and (2) the magnitude of sea level changes since deglaciation.
Notably, we have found that at Calvert Island (home of the Hakai Institute), relative sea level has barely fluctuated since deglaciation and as a result, was a prime location for early peoples.
Eamer, J.B.R., Shugar, D.H., Walker, I.J., Neudorf, C., Lian, O. Eamer, J., Bryce, J., Biln, L. In press. Late Quaternary landscape evolution in a region of stable postglacial relative sea-levels, British Columbia central coast. Boreas. DOI: 10.1111/bor.12297
McLaren, D., Fedje, D., Hay, M., Mackie, Q., Walker, I.J., Shugar, D.H., Eamer, J.B.R., Lian, O.B., and Neudorf, C. 2014. A postglacial sea-level hinge on the central Pacific coast of Canada. Quaternary Science Reviews, 97: 148-169. DOI: 10.1016/j.quascirev.2014.05.023
Shugar, D.H., Walker, I.J., Lian, O.B., Eamer, J.B.R., Neudorf, C., McLaren, D., and Fedje, D. 2014. Post-glacial sea-level change along the Pacific coast of North America. Quaternary Science Reviews, 97: 170-192. DOI: 10.1016/j.quascirev.2014.05.022