Observations of iceberg rafting in Glacier Bay, Alaska, and the identification of ancient ice-rafted deposits
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Abstract
Observations of icebergs in a modern glacial marine environment indicate that ancient rocks that received iceberg-rafted material should contain: (1) local concentrations of stones that originated when icebergs overturned, and (2) small pellets of till that were originally sediment filling the spaces between clear ice crystals.
The till pellets are especially significant in identifying an ancient glacial setting because they originate through a process unique to glaciers—the flow-and recrystallization-induced segregation of originally disseminated fine sediment. Thus when freed by melting and deposited by iceberg rafting, the pellets would reliably indicate the presence of glacial ice in an ancient environment. In the Gowganda Formation, a Precambrian glacial deposit, strata that contain outsized, presumably iceberg-rafted stones also contain abundant small flattened clasts of unsorted graywacke interpreted as the lithified counterparts of the till pellets observed on modern icebergs.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Observations of iceberg rafting in Glacier Bay, Alaska, and the identification of ancient ice-rafted deposits |
| Series title | Bulletin of the Geological Society of America |
| DOI | 10.1130/0016-7606(1970)81[891:OOIRIG]2.0.CO;2 |
| Volume | 81 |
| Issue | 3 |
| Year Published | 1970 |
| Language | English |
| Publisher | Geological Society of America |
| Description | 4 p. |
| First page | 891 |
| Last page | 894 |
| Country | United States |
| State | Alaska |
| Other Geospatial | Glacier Bay |
| Google Analytic Metrics | Metrics page |