1. Eustatic sea level has fluctuated between -120 and 200 meters relative to modern sea level over the Phanerozoic Eon (542 Ma – Present).

2. Causes of Eustatic (Global) or Relative Sea Level Change 1.Tectonism- Largest and most gradual changes. Caused by changes in the volume or holding capacity of the ocean basins. Rates of sea floor spreading have the greatest impact on impact on ocean basin holding capacity. The volume of mid-ocean ridges increase during periods of high sea floor rates; thus resulting in higher eustatic sea level values, such as the transgression (rise in eustatic sea level) during the Cretaceous Period. The Tertiary Period marine regression (fall in eustatic sea level) was likely related to the enlargement of the Atlantic Ocean basin and the denser ocean crust distal of the spreading ridge. 1.Ice Sheet Growth and Decay- The growth and melting of land ice is responsible for the second major cause of eustatic sea level change, and the most dominant during the Quaternary Period (prior 2 million years). As ice sheets build up sea level lowers ~1 m/1000 years. Maximum lowering was ~120-150 m during the most extensive glacial cycles. As the ice sheets rapidly decay sea levels rises at an average rate of 5-10 m/1000 years. Ice sheet growth and decay also influences the water mass over the ocean basins. 1.Local isostatic and tectonic effects which primarily affect a local setting. These relative sea level effects are primarily due to glacio-isostasy (ice loading and unloading effects) and hydro-isostasy (water loading and unloading effects).

3. Causes of Eustatic (Global) or Relative Sea Level Change 1.Tectonism- Largest and most gradual changes. Caused by changes in the volume or holding capacity of the ocean basins. Rates of sea floor spreading have the greatest impact on impact on ocean basin holding capacity. The volume of mid-ocean ridges increase during periods of high sea floor rates; thus resulting in higher eustatic sea level values, such as the transgression (rise in eustatic sea level) during the Cretaceous Period. The Tertiary Period marine regression (fall in eustatic sea level) was likely related to the enlargement of the Atlantic Ocean basin and the denser ocean crust distal of the spreading ridge. 1.Ice Sheet Growth and Decay- The growth and melting of land ice is responsible for the second major cause of eustatic sea level change, and the most dominant during the Quaternary Period (prior 2 million years). As ice sheets build up sea level falls ~1-3 m/1000 years. Maximum lowering was ~120-150 m during the most extensive glacial cycles. As the ice sheets rapidly decay sea levels rises at an average rate of 5-10 m/1000 years. Ice sheet growth and decay also influences the water mass over the ocean basins. 1.Local isostatic and tectonic effects which primarily affect a local setting. These relative sea level effects are primarily due to glacio-isostasy (ice loading and unloading effects) and hydro-isostasy (water loading and unloading effects).

4. Eustatic sea level has gradually lowered since the Cretaceous transgression. The development of continental ice sheets has had major impact on shorter term fluctuations as the ice sheets have grown and decayed. The largest fluctuations occurred following the build-up of ice sheets on the northern hemisphere continents.

5. Causes of Eustatic (Global) or Relative Sea Level Change 1.Tectonism- Largest and most gradual changes. Caused by changes in the volume or holding capacity of the ocean basins. Rates of sea floor spreading have the greatest impact on impact on ocean basin holding capacity. The volume of mid-ocean ridges increase during periods of high sea floor rates; thus resulting in higher eustatic sea level values, such as the transgression (rise in eustatic sea level) during the Cretaceous Period. The Tertiary Period marine regression (fall in eustatic sea level) was likely related to the enlargement of the Atlantic Ocean basin and the denser ocean crust distal of the spreading ridge. 1.Ice Sheet Growth and Decay- The growth and melting of land ice is responsible for the second major cause of eustatic sea level change, and the most dominant during the Quaternary Period (prior 2 million years). As ice sheets build up sea level rises ~1 m/1000 years. Maximum lowering was ~120-150 m during the most extensive glacial cycles. As the ice sheets rapidly decay sea levels rises at an average rate of 5-10 m/1000 years. Ice sheet growth and decay also influences the water mass over the ocean basins. 1.Local isostatic and tectonic effects which primarily affect a local setting. These relative sea level effects are primarily due to glacio- isostasy (ice loading and unloading effects) and hydro-isostasy (water loading and unloading effects).

6. Ice loading can produce major isostatic adjustments to the lithosphere as the ductile asthenosphere is displaced outward from the ice load. As the major ice sheets retreat the asthenosphere will slowly flow back causing the lithosphere to rise. Returning ocean water will also have corresponding isostatic effects.

7. Sea Level Reconstructions Coral reefs Raised and Drowned Deltas Drowned river valleys Paleoshoreline Indicators (marine terraces) Marine Oxygen Isotope Records (Global Ice Volume Records)

10. Coral reefs will drown if sea level rise is too rapid for the growth rate to keep up with the rising water. Coral reefs grow at rates between 0.8 and 80 mm/ year.

12. Drown reef complexes found off the coast of Hawaii were likely a casualty of meltwater pulse 1A between 14,700 and 14,200 years ago.

13. Tectonically uplifted terraces dated along the Huon Peninusula, Papua New Guinea document marine high-stands formed during interglaciations.

15. Ice loading can produce major isostatic adjustments to the lithosphere as the ductile asthenosphere is displaced outward from the ice load. As the major ice sheets retreat the asthenosphere will slowly flow back causing the lithosphere to rise. Returning ocean water (from melting ice) will also have corresponding isostatic effects. The magnitude and rate of isostatic depression and recovery will be related to the thickness of the ice sheet, thickness of the lithosphere and viscosity of the mantle.

16. Relative sea level change in a previously glaciated regions will be dependent upon eustatic sea level change and isostatic effects.

17. Post-glacial marine terraces on San Juan Island, Washington: A product of multiple Meltwater Pulses 1A Hope Sisley, Terry Swanson, John Stone University of Washington

21. Upper Terrace Lower Terrace Terraces form when relative sea level is stable. How would you reconcile terrace formation on San Juan during a period of rapid isostatic uplift (i.e., 10-20 cm/yr)?

22. Be-10 dated till boulders on Cattle Point moraine and terraces.

23. 1B 1A

28. Late wisconsinan glaciomarine deposition & isostatic rebound, N.puget lowland, WA D.P.Dethier et al., 1995

29. Fig.1.Puget Lowland

30. Scope Events between 13.6k - 11.3k years ago in the Puget Lowland: – Rapid retreat of cont.ice – Everson marine incursion – High rates of isostatic rebound http://www.washington.edu/burkemuseum/w aterlines/glaciation.html http://www.washington.edu/burkemuseum/w aterlines/glaciation.html

31. Study Emphasis Glaciomarine Deposits – Distribution – Stratigraphy – Paleoecology – Geochemistry Ice recession, marine incursion, isostatic rebound – Geomorphic evidence – 14 C evidence

32. Fig.5.Glaciomarine deposits, inferred depositional mechanisms and environments. Modern analog in coastal Alaska.

33. Facies Proximal Transitional Distal Marine and Estuarine Emergence

34. Relative sea level can be determined using geomorphic features such wave-cut terraces, topset beds of marined deltas, and relict channels on Whidbey Island.

35. Proximal Facies Sorted deposits generally become finer from N to S in the moraines Preserved thicknesses as much as 100m Kettled landscape

36. Transitional Facies -Finer grained -Richer in dropstones -More diverse fauna -1-10km away from ice margins -Pebbly silt, 3-10m thick -Locally rich in fossils of invertebrates -Accumulated at about the same time as proximal facies

37. Distal Facies >10km away from ice margins Absence of dropstones suggests that about 13.5k years ago, the floating ice was uncommon near Marysville, and did not reach Mt.Vernon

38. Marine and Estuarine Facies -Thin, fine grained -Shallow, subtidal origin for sandy sediment overlying pebbly silt marine facies ice-rafted pebbly silt ice-proximal (flow till) emergent facies

39. Emergence Facies Emergence of land, shallowing of water Contain boulder lags and finer sandy deposits Wave-cut surfaces emergent facies ice-rafted pebbly silt

40. Fig.6.Stratigraphy and lithology of Everson-age deposits

41. Fraser Glaciation (25k-10k y ago) Cont.ice attained thickness of ~1700m at the Int’l boundary (Canadian border), and about 1200m near Everett The retreat of ice took only a few hundred years, caused – rapid glacio-isostatic rebound – marine incursions (over 10 000km 2 of WA) – deeply embayed margins on ice lobes

42. Fig.2. Marine limit at ~13.5ka

43. Fig.3.Altitude of marine limit in Puget Lowland, in meters

44. Fig.4. Stratigraphy of Everson-age deposits. Site 1-Mt.Vernon N Site 2-Mt.Vernon S

45. Fig.4.(continued) Site 3-Big Lake Site 4-Davis Bay Site 5-Cattle Point Site 6-Marysville

46. Isostatic Rebound Present day land area S from Everett lay above sea level Present day area N of Everett was covered by 40 to >150m of marine water After the ice progressively retreated, most of the uplift was occurring within ~3.5k years The relative sea level fall persisted 3-6k years, since rebound rates exceeded eustatic sea level rise before 7k years ago

47. Fig.7.Maximum altitude of marine limit from Everett to Int’l Boundary