Channel

Delta or fan

Delta or fan

DEEP INFRALITTORAL: 5 m–30 m water depth

Wall

Delta or fan

Floor

SHALLOW INFRALITTORAL: 0 m–5 m water depth

LIST OF MAP UNITS

Floor

Moraine

Rock outcrop or wall

Slump

Delta or fan

Floor

Moraine

Rock outcrop or wall

Slump

Moraine

CIRCALITTORAL (OFFSHORE): 80 m–200 m water depth

CIRCALITTORAL: 30 m–80 m water depth

Slump

Floor

Moraine

Rock outcrop or wall

Channel

MESOBENTHIC: 200 m–1,000 m water depth

Delta or fan

Floor

Moraine

Rock outcrop or wall

Slump

Scientific Investigations Map 3253

Sheet 2 of 4

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey

Discussion

 This map shows the primary morphologic features within West Arm, Glacier 

Bay National Park & Preserve, Alaska. The Coastal and Marine Ecological Classification Standard (CMECS, Madden and others, 2009) by the National Oceanic and 

Atmospheric Administration (NOAA) and NatureServe was used to classify various 

submarine landforms. Geoforms were manually selected from the multibeam 

bathymetry with the aid of video observations, seismic reflection profiles, bottom 

grab descriptions, knowledge of glacimarine processes, well-documented glacial 

history in the West Arm, and interpretations from other studies (for example, Cai, 

1994).

 Units displayed on this map represent the geoform component of the 

CMECS classification draped over the shaded-relief multibeam bathymetry. Geoforms shape the seascape and provide structure and channel energy, regulate 

bioenergetics, and control transfer rates of energy, material, and organisms 

(Madden and others, 2009). Geoforms are defined based on spatial scales ranging 

from megageoform (largest) to microgeoform (smallest). All units depicted in this 

map are mesogeoform scale, as they range in size from tens of meters to kilometers. All geoforms displayed are part of the megageoforms of continental margin 

and fjord. Smaller-scale landforms within the mesogeoform scale exist within the 

map units, including channel, slump, rock outcrop, and fan. Each geoform is divided 

into its respective CMECS benthic depth zone: shallow infralittoral (0–5 m), deep 

infralittoral (5–30 m), circalittoral (30–80 m), circalittoral (offshore) (80–200 m), and 

mesobenthic (200–1,000 m). Bathymetric contours represent the divisions between 

these depth zones. As water depth increases, the shade of color for each geoform 

darkens. 

 Deltas depicted are both fluvial and fully glacifluvial in origin and most are 

at least partially fed by glacial meltwater runoff. Morainal forms include kame 

terraces, morainal banks, push moraines, and complexes composed of multiple 

superimposed features, which formed in contact with and proximal to the terminus. 

Lithologically heterogenous, morainal banks are composed of poorly sorted sand 

and gravel, weakly stratified to massive diamicton, and stratified sand and mud. 

Seismic reflection profiles indicate that many of the prominent morainal banks within 

the West Arm are cored by bedrock and are therefore sills (Cai, 1994). Relict 

moraines are typically draped in distal mud, except where high-energy processes 

disrupt hemiplegic sedimentation, as in the tidally winnowed shallows of Hugh Miller 

Inlet. Similarly, rock outcrop and wall classes imply that the underlying morphology 

of the feature is bedrock controlled; however, owing to the large influx of glaciallysourced mud, even steeply-sloping bedrock features may have an extensive mud 

 drape. (See the accompanying pamphlet for a more detailed discussion of substrate

 relations for each geoform.) 

137°0' 136°30' 136°0' 135°30' 135°0'

59°0'

58°30'

58°0'

Pacific

Ocean

Glacier

Bay

Sheet 4

Location map showing CMECS geoform component maps 

of lower West Arm (this map, red) and upper West Arm (sheet 4, 

black), Glacier Bay National Park and Preserve, Alaska.

136°15'

136°15'

136°20'

136°20'

136°25'

136°25'

136°30'

136°30'

136°35'

136°35'

136°40'

136°40'

136°45'

136°45'

58°55'

58°55'

58°50'

58°50'

58°45'

58°45'

58°40'

58°40'

Inlet

West

Arm

Rendu

Queen

Inlet

Tidal Inlet

Hugh Miller

Inlet

View 1. Perspective view looking north over the submarine fan at the mouth of Queen Inlet, a large hanging valley that intersects the mainstem of 

the West Arm. Owing to the high influx of sediment from nearby Carroll Glacier (visible in the background), Queen Inlet is one of the most dynamic 

environments in the lower West Arm, with a mean sediment accumulation rate of roughly 0.3 m/yr. The Queen Inlet Fan (foreground) is fed by a 

10-km-long submarine channel, incised into the Holocene fill on the fjord floor (Carlson and others, 1989). Sediment is transported to the fan by way 

of turbidity currents, originating along the unstable slopes of the fjord head delta and by slumps and mudflows derived from unconsolidated 

sediment deposited on the steep walls of the inlet. The ripple-like structures visible on the surface of the fan are interpreted as compressional 

ridges, resulting from plastic deformation. Queen Inlet was formerly occupied by Carroll Glacier, which retreated to the head of the Inlet by the late 

1800s. The submarine fan is believed to have begun forming shortly afterwards, associated with the growth of the Queen Inlet delta (Carlson and 

others, 1999). Vertical exaggeration in the perspective view, X1.5.

View 2. Perspective view looking south over the entrance to the West Arm and Hugh Miller Inlet. Seismic-reflection profiles indicate that this 

relatively shallow area sits atop bedrock and preglacial sediment (Cai, 1994). The extent of the mapped region roughly corresponds with the 1860 

position of the terminus. Water depths here are the greatest in Glacier Bay, with many parts of the floor over 400 m below sea level. Consequently, 

the terminus occupied this position briefly during the 1860s as it rapidly retreated to the shallower inlets of the upper West Arm. Estimates of the 

rate of retreat through this interval are constrained by the 1879 position of the terminus, suggesting an average rate of retreat of 1.8 km/yr (Carlson 

and others, 1999). Cai (1994) identifies seven morainal banks deposited within this interval (one visible near the mouth of Tidal Inlet towards the left 

edge of the image), indicative of brief periods of quasi-stability punctuating the otherwise rapid retreat. Deglaciation of the shallower Hugh Miller 

Inlet appears to have occurred in a markedly different style. The morphology of this area indicates extensive down-wasting of relatively clean ice. 

During this interval, this branch of the Russell System would have maintained a relatively stable terminus, depositing the morainal complex visible at 

the mouth of Hugh Miller Inlet. Vertical exaggeration in the perspective view, X1.5.

2

1

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the 

U.S. Government

This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary between electronic plotters 

and between X and Y directions on the same plotter, and paper may change size due to atmospheric conditions; therefore, scale and 

proportions may not be true on plots of this map.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sim/3253/

Suggested Citation: Hodson, T.O., Cochrane, G.R., and Powell, R.D., 2013, Marine Benthic Habitat Mapping of the West Arm, Glacier 

Bay National Park and Preserve, Alaska: U.S. Geological Survey Scientific Investigations Map 3253, pamphlet 30 p., scale 1:50,000, 

available at http://pubs.usgs.gov/sim/3253/.

MAP LOCATION

ALASKA

SCALE 1:50000

2 1 0 2 KILOMETERS

2000 0 2000 4000 6000 8000 10000 12000 14000 FEET

2 1 0 2 MILES

LAND CONTOUR INTERVAL 100 METERS

BATHYMETRIC CONTOURS: 30, 80, AND 200 METERS

SEA LEVEL, CYAN

CMECS Geoform Component Map of Lower West Arm, Glacier Bay National Park and Preserve, Alaska

By

Timothy O. Hodson1, Guy R. Cochrane2, Ross D. Powell1 

2013

APPROXIMATE MEAN

DECLINATION, 2013

21°

MAGNETIC NORTH

TRUE NORTH

Base from U.S. Geological Survey, National Elevation Dataset

NASA Landsat 7 Imagery, 1999

Universal Transverse Mercator Zone 8N Projection, WGS84

NOT INTENDED FOR NAVIGATIONAL USE

Manuscript approved for publication March 6, 2013

GIS database and digital cartography by 

T.O. Hodson 

Based on multibeam sonar data collected in

2009 during NOAA NOS hydrographic surveys 

H12140, H12141, and H12142

1 Department of Geology and Environmental Geosciences, Northern 

Illinois University

Pacific Coastal and Marine Science Center, U.S. Geological Survey 2