DOI: 10.5066/p9wda76u
title: Digital compilation of historical ice terminus positions of tidewater glaciers in Glacier Bay National Park and Preserve, Alaska

description: In coastal subarctic environments such as the fjords of Southeast Alaska, tidewater glaciers can control local hydrology, climatic patterns, ecology, and geologic hazards like landslides and consequent tsunami waves. Documenting and studying glacial retreat in fjords can help scientists understand the dynamic systems that are intrinsically tied to glacial ice processes and forecast changes in these systems. Detailed inventories of glacial retreat have been produced using satellite images and other remote data spanning back to the mid-1900s. However, compiling data on ice positions from before the availability of remotely sensed data requires the existence of historical observations and surveys; oral or written accounts; or geomorphic interpretations using dating techniques such as tree rings or radiocarbon ages. In Glacier Bay National Park and Preserve, Alaska (GBNPP), a rich history of exploration and scientific research has provided us with three centuries? worth of documentary evidence for glacier extents. This documentation stands in contrast to other areas in Alaska that have limited to no historical data. Historical maps and accounts of Glacier Bay have documented some of the world?s fastest glacial ice retreat since the Little Ice Age (LIA) and have supported studies on topics including glacial sedimentology, post-ice ecological changes, and landslide hazards in glacial and periglacial environments (e.g., Powell, 1981; Koppes and Hallet, 2002; Milner et al., 2007; Wieczorek et al., 2007). Recently, the data comprising this data release were used to constrain maximum submarine landslide ages for landslide susceptibility mapping in Glacier Bay (Avdievitch and Coe, 2022). This data release includes digitized and compiled historical ice terminus positions for GBNPP�from the 1700s to the late-1900s. More recent calving front positions (1972 through about 2012) based on remotely sensed observations are available in McNabb and Hock (2014), with select terminus positions from their dataset included here for context. We mapped additional terminus positions from 2019 using lidar (U.S. Geological Survey, 2021). For this data release, ice terminus positions were compiled from historical sources and digitized using a geographic information system. A polyline shapefile includes each ice terminus position with attributes detailing the year, the source(s) of the data, and notes on interpretation, uncertainty, or caveats associated with each terminus position. Special reference is due to Powell (1980), who first compiled most of the historical terminus positions in Glacier Bay proper in analog form, and on which much of this database is based. Revisions, additions, and notes on Powell?s work are detailed in the accompanying attributes and metadata. These data are meant to serve as a practical summary of available data showing ice retreat in Glacier Bay National Park and Preserve from the Little Ice Age through 2019. Data generally portray glacial retreat on decadal time scales and on a regional (Park-wide) spatial scale, based on sources available to the authors at the time of release. Some areas were historically surveyed more frequently and precisely than others, so any additional localized study of ice retreat in a specific area should consult the primary and secondary sources attributed herein for a better understanding of positional and temporal uncertainties. The authors do not claim any accuracy or completeness of this database beyond what is presented in the original sources (for historical data) or what is resolvable given the resolution and accuracy of the 2019 lidar. References Cited Avdievitch N. N., and Coe JA, 2022, Submarine Landslide Susceptibility Mapping in Recently Deglaciated Terrain, Glacier Bay, Alaska: Frontiers in Earth Science v. 10, p. 821188. https://doi.org/10.3389/feart.2022.821188 Koppes, M.N., and Hallet, B., 2002, Influence of rapid glacial retreat on the rate of erosion by tidewater glaciers: Geology, v. 30, no. 1, p. 47?50. https://doi.org/10.1130/0091-7613(2002)030&lt;0047:IORGRO&gt;2.0.CO;2 McNabb, R.W., and Hock, R., 2014, Alaska tidewater glacier terminus positions, 1948-2012: Journal of Geophysical Research: Earth Surface, v. 119, no. 2, p. 153?167. https://doi.org/10.1002/2013JF002915 Milner, A.M., Monaghan, K., Flory, E.A., Veal, A.J. and Robertson, A., 2007, Ecological development of the Wolf Point Creek watershed; a 25-year colonization record from 1977 to 2001: in Piatt, J.F., and Gende, S.M., eds., in Proceedings of the Fourth Glacier Bay Science Symposium: U.S. Geological Survey Scientific Investigations Report 2007-5047, p. 3 -7. https://doi.org/10.3133/sir20075047 Powell, R.D., 1980, Holocene glacimarine sediment deposition by tidewater glaciers in Glacier Bay, Alaska: Columbus, Ohio, Ohio State University, Ph.D. dissertation, 420 p. Powell, R.D., 1981. A model for sedimentation by tidewater glaciers. Annals of Glaciology, 2, p. 129-134. https://doi.org/10.3189/172756481794352306 U.S. Geological Survey, 2021, USGS 3D Elevation Program. https://apps.nationalmap.gov/downloader/. Wieczorek, G.F., Geist, E.L., Motyka, R.J., and Jakob, M., 2007, Hazard assessment of the Tidal Inlet landslide and potential subsequent tsunami, Glacier Bay National Park, Alaska: Landslides, v. 4, no. 3, p. 205?215. https://doi.org/10.1007/s10346-007-0084-1