CChapter Two: Environmental Setting by J. David McMahan
Location and Physiography
Sitka is located on the west coast of Baranof Island, one of the largest of the numerous
islands that comprise the Alexander Archipelago of southeastern Alaska. Baranof
Island extends some 105 miles between Peril Strait to the north
and Christian Sound to the south. It is bordered on the east by
Chatham Straight and on the west by the Pacific Ocean. Although
Sitka is located on the outer coast, the community is sheltered
from the direct impact of storms by Kruzof Island and several
smaller islands to the north and west (Figure 2). These islands
form the north and west sides of Sitka Sound.
Figure 2.1. An aerial view of Sitka, looking northwest,
circa 1945-1955. Castle Hill is in the foreground
at left. (Photo Shop Studio, Sitka. Photo postcard in the collection of Dave McMahan).
Physiographically, Baranof Island is within the Chilkat-Baranof
Mountains Section of the Pacific Border Ranges Province (Wahrhaftig
1965:42). This province consists of several mountain ranges along
the Pacific Coast, along with an adjacent coastal shelf. The Chilkat-Baranof
Mountains Section, a highland of diversified topography, has been
subdivided into four subsections: the Alsek Ranges, Glacier Bay,
Chichagof Highland, and Baranof Mountains. Sitka is located in
the Baranof Mountains subsection, a rugged asymmetric chain 3,000-5,300
feet in altitude, having a steep eastern slope and a more gentle
southwest slope deeply indented by fiords (Wahrhaftig 1965:42).
Drainage in this subsection is via short, swift streams that flow
directly to the ocean. Indian River, which flows into Sitka Sound
between Crescent and Jamestown Bays, drains a watershed of about
12.6 square miles (SNHP 1998:101). This small river, which originates
in the mountains of central Baranof Island, is the largest freshwater
stream in the community of Sitka. Cirque glaciers and small icefields
are located on mountains higher than 4,500 feet on Baranof Island.
Permafrost is nonexistent.
Castle Hill, strategically overlooking Sitka Sound, has long been a defining landmark of the local landscape. This majestic 60-foot-high promontory is a rocky headland typical of the erosional landforms which characterize coastal southeast Alaska. Formed by differential weathering of geologic strata by wave action, it was once cut off from the mainland by the highest tides. Due to filling and parking lot construction around the base of the hill in the 1960s, and the construction of a towering bridge to Japonski Island around 1970, the hill has lost much of its dramatic appearance. However, it remains a popular overlook for viewing Sitka Sound and the town of Sitka (Figure 3).
Figure 2.2. A view of Castle Hill
looking north, 1998.
Geology and Soils
Geological survey and mapping of northern Baranof Island in
the early 1960s has provided baseline data on the type, age, and
stratigraphy of rock formations in the vicinity of Sitka (Berg
and Hinckley 1963; Loney, et. al. 1964). Such mapping is useful
to archaeologists attempting to identify source materials available
for tool manufacture by pre-contact inhabitants of the area. Geologic
deposits in the region are believed, based on correlations with
adjacent areas, to range in age from Paleozoic to Mesozoic (Berg
and Hinckley 1963:01). The strata are tightly folded, intricately
faulted, and regionally metamorphosed. Bedded gneiss and schist
predominate along the shore of Peril Strait. Dark-green and dark-gray
amphibole-rich rocks, interlayered with metachert and subordinate
marble, form a northwest-trending belt about a mile wide along
the southwest coast of Catherine Island, Dead Tree Island, and
part of the southwest shore of Portage Arm (ibid:3-5). A geologic
complex termed the Nakwasina Group, comprised primarily of metachert,
volcanic rocks, and greenstone, outcrops along a portion of the
western shore of northern Baranof Island (ibid:6-9). Another geologic
complex, termed the Kelp Bay Group, is widespread on northern
Baranof Island, forming the shoreline from north of Rodman Bay
to Kasnyku Bay and from Louise Cove to north of the mouth of St.
John Baptist Bay (ibid:10). This group is mostly comprised of
fine-grained thin- to medium-bedded rocks that include fissile
quartzose greenschist and phyllite, graywacke, slate and sheared
conglomerate, calcareous and quartzose slate with scattered lenses
of metachert and volcanic rock, and granular moderately platy
siliceous greenschist interbedded with jasper or slate and argillite
lenses (ibid). Mesozoic age outcrops in the immediate vicinity
of Sitka, probably including Castle Hill, have been termed the
Sitka Group by Berg and Hinckley (1963:12-14). The Sitka group
consists of a thick sequence of slate, graywacke, and conglomerate
that crops out from Old Sitka (6 miles north of Sitka) southeastward
to Silver Bay and makes up many of the smaller islands near Sitka.
Principal rock types of this group are "thin- to medium-bedded
interstratified graywacke and argillite and slaty argillite"
(ibid:13). Conspicuous outcrops from Old Sitka to Sitka are comprised
of beds of massive graywacke, conglomerate, and breccia as much
as 50 feet thick. Overlying the Sitka Group on the south half
of Kruzof Island are post-glacial basaltic and andesitic lava
and pyroclastic debris from Mount Edgecumbe (ibid:14-15).
Overlying the bedrock on northern Baranof Island are unconsolidated deposits of alluvium, glacial debris, and volcanic ash. In Sitka, the Indian River delta and much of Sitka National Historical Park is comprised of alluvium that has been reworked by marine processes (SNHP 1998:100). Regional uplift has occurred over the last 9,000 years due to isostatic rebound, tectonic forces, and compression of crustal plates (ibid:100-101). This, coupled with local volcanic activity or earthquakes, has resulted in the uplift of the Indian River delta along with beaches, flood plains, and abandoned channels (Chaney, Betts, and Longenbaugh 1995). Land in the Sitka area is now rising at a rate of approximately 0.12 inches (0.3 cm) per year (SNHP 1998:101).
Soil development in southeast Alaska has been influenced by climate, topography, parent material, drainage, organisms, and time. They are typically classified as spodosols. Soils around Sitka have been classified by Rieger et al. (1979:152-154) as "typic cryohumods, loamy, hilly to steep humic cryorthods, very gravelly, hilly to steep." This soil association is found on steep hills in areas that are largely covered by volcanic ash from Mt. Edgecumbe (ibid). The ash is many feet thick in lower areas, where it overlies glacial till, but is thinner on higher slopes due to erosion. During the 1995 testing program on top of Castle Hill, stratified soils believed to be of volcanic origin were identified below cultural deposits. Soils on and around Castle Hill consist largely of organic-enriched cultural deposits. It appears that reworked cultural soils were moved from the slopes to the top of the hill during construction of the agricultural research building in 1898. In some areas, these overlie primary cultural deposits and preserved volcanic soils. Considerable variation occurs across the top of the hill, however, where cultural deposits rest directly on the high points of undulating bedrock in some locations. On the natural terrace near the southeast base of the hill, where intensive archaeological investigation occurred, highly organic cultural deposits were underlain directly by sterile gravels. These probably date from the end of the Pleistocene (i.e., around 8,000 to 10,000 years ago), when sea levels ranged up to 15 meters higher along the Pacific Northwest coast than at present (Clague et al. 1982; Swanston 1967).
Baranof Island is within a Western hemlock Sitka spruce
(Picea sitchensis Tsuga heterophylla) forest
ecosystem (Viereck and Little 1972:detached map; Viereck and Dyrness
1980; Viereck, et al. 1982). This is the coastal temperate, closed-canopy
rainforest that is typical of southeast Alaska. Understory components
include: blueberry/huckleberry (Vaccinium spp.) thickets,
devils club (Oplopanax horridum), skunk cabbage (Symplocarppus
foetidus), dwarf dogwood (Cornus canadensis), watermelon
berry (Streptopus amplexifolius), and ferns. Disturbed
areas support a dense growth of alder (Alnus spp.) and
wild celery (Heracleum lenatum). A more complete list of
understory plants is presented in Table 1. Due to extensive clearing
and logging in the 19th and 20th centuries, few areas of old growth
forest are preserved around Sitka. Some of the largest trees in
the area are found in the northeast corner of Sitka National Historical
Park, where scattered stumps provide evidence of only selective
logging (SNHP 1998:103). Old growth characteristics in this area
include multiple canopy layers, trees of varying diameters, dead
standing trees, and woody debris (ibid). Because this area was
once used as an artillery target range by the U.S. military, loggers
may have avoided extensive timber harvest due to the potential
for sawmill damage by the shrapnel said to be imbedded in the
trees (Joe Ashby, personal communication 1997). Descriptions of
the original old growth forest are provided in early 19th century
descriptions by visitors to Sitka, such as the account which resulted
from naturalist Baron von Kittlitzs 1827 visit:
The woods consist for the most part of two kinds of stately spruce Pinus canadensis, L. [i.e., Sitka Spruce, Picea sitchensis], and P. Mertensiana, Bongard [i.e., Western Hemlock, Tsuga heterophylla]... Here and there in these swampy patches [at the base of Harbor Mountain] grow many of the well known North American tamarack (Pinus palustris) [spruce?], here a bit stunted; whereas the forest proper looms very high, giving the towns surroundings a magnificent wild appearance... A very typical characteristic of the trees here is their inclination to grow like parasites on their own kind. The forest floor was covered all over with more or less well preserved logs and roots of trees, some of which had fallen over a long time before, on which grew not only shrub like Baccinia and high, very picturesque tussocks, but also numerous young seedlings of the forest trees in lush abundance. Obviously the remains of the former trees had long since turned into fertile earth and housed the roots of tall younger trees even though they themselves were still covered by bark and retained their outer layer altered little or not at all. Lush carpets of moss and various lichen covered the earth formed from such remains, which were profusely covered in shady places by white flowers marked purple-black on the inside, probably Corvus canadensis or C. Succica [i.e., dwarf dogwood, Cornus canadensis]. Many carmine-red flowers of the salmonberry (Rubus spectabilis), whose fruit we saw ripening later in July, were still in bloom [Kittlitz 1987:131-132].
Table 2.1. Common understory plants of Alaskan hemlock-spruce forests.
The present second growth forests around Sitka are the product
of extensive logging throughout the 19th and 20th centuries. Evenby 1827, Kittlitz (1987:132) noted that the
best trees had been "felled long ago for building purposes."
Following the founding of New Archangel, Baranov attempted to
burn the surrounding forests which provided ambush locations for
the Tlingit, but his efforts were largely unsuccessful due to
the dampness (Litke 1987:45). Extensive timber harvest for buildings,
ships, firewood, and charcoal continued throughout the Russian
occupancy of Sitka. Rakestraw (1981:4), in writing a history of
the U.S. Forest Service in Alaska, noted that yellow-cedar (
Chamaecypari nootkatensis) was depleted around Sitka, but that impacts to Alaska forests
in general were insignificant. The most significant impacts to
old growth forests around Sitka occurred with the development
of technology which allowed widespread clear-cutting, the development
of logging into a major regional industry, and the construction
of a large sawmill and pulp mill at Sitka during the 1950s.
Important terrestrial mammals of the Coastal Western HemlockSitka
Spruce forest community include masked shrew, dusky shrew, little
brown bat, red squirrel, northern flying squirrel, deer mouse,
red-backed vole, long-tailed vole, porcupine, gray wolf, black
bear, brown bear, pine marten, ermine, wolverine, lynx, Sitka
black-tailed deer, and mountain goat (Selkregg 1976:128). Important
species of the freshwater community include water shrew, beaver,
northern bog lemming, tundra vole, muskrat, mink, and river otter
(Selkregg 1976:138). Major marine mammal species in Sitka Sound
include harbor seal, sea otter, sea lion, and several species
of whale (Selkregg 1976:134, Figure 130). A more complete list
of marine species in the southeast Alaska region is presented
in Table 2. Birds associated with southeast Alaska coastal forests
include goshawk, sharp-shinned hawk, bald eagle, blue grouse,
great horned owl, rufous hummingbird, hairy woodpecker, downy
woodpecker, western flycatcher, Stellers jay, common raven,
chestnut-backed chickadee, winter wren, varied thrush, hermit
thrush, golden-crowned kinglet, ruby-crowned kinglet, Townsends
warbler, pine grosbeak, and pine siskin (Selkregg 1976:128). Several
high density areas for waterfowl occur within Sitka Sound (Selkregg
1976:134, Figure 130). The numerous waterfowl species are included
in Table 2. Saltwater and anadromous fish of the region include
walleye pollock, Pacific cod, sablefish, Pacific pomfret, Pacific
herring, albacore, sockeye (red) salmon, coho (silver) salmon,
chinook (king) salmon, chum (dog) salmon, pink (humpback) salmon,
steelhead trout, black rockfish, Pacific ocean perch, eulachon,
sculpins, halibut and other flatfishes, and salmon shark (Selkregg
1976:136). Freshwater fish (excluding the anadromous fish reported
above) include cutthroat trout, rainbow/steelhead trout, dolly
varden char, sculpins, and northern pike (Selkregg 1976:138).
Locally, pink and chum salmon spawn in the intertidal and lower
floodplain portions of Indian River from mid-July through September,
while coho salmon, steelhead trout, and dolly varden char migrate
upstream (SNHP 1998:104).
It was the abundance of fur-bearing mammals, particularly the large sea otter populations, which prompted Russian exploration and settlement along the North Pacific coast. Shortly after the founding of New Archangel, Langsdorff (1993:57-61) described some of the more important land mammals, sea mammals, birds, and marine resources of the region:
Mammals found here include whales, seals, sea lions, sea,
marsh, and river otters, brown and black bears. The latter I
have never had an opportunity to examine closely. On account
of the size and the nature of the fur I have often seen, I have
concluded that the American black bear must be a very different
species from the brown bear...
Individual birds belonging to this species of beautiful, white-headed, white-tailed eagles can be seen here almost the entire year... Their meat is edible.
The Russians, in the first year after their arrival, here killed and ate two hundred of them. I have often stilled my hunger with their meat and found it tasty. The intestines have to be carefully removed. The liver is said to be very harmful, indeed, even poisonous [Langsdorff 1993:57-60].
Table 2.2. Marine species of the southeast Alaska region.
The naturalist von Kittlitz (1987:132-148), who visited Sitka
in 1827, also described the birds and fish of the region in some
detail. By that time, he reports that the economically important
sea otter was already disappearing due to harvesting for trade