Very little qualitative change’in type of streambed material is 
apparent on any of the study streams. Stream sections mapped in 1949 
as consisting of sand and gravel were also mapped as sand and gravel 
in subsequent years. An intensification of this phase of the study 
was begun in 1955 with the installation of silt traps and sampling of 
gravel. 
MOVEMENT OF FRAGMENTAL DEBRISL8/ IN AN INTERTIDAL ZONE 
The intertidal zonesl9/ of many streams in Southeast Alaska, as well 
as elsewhere, are widely used by pink salmon as spawning areas (9). 
A high percentage of the total number of pink salmon using Harris River 
and Indian Creek spawn in the riffle area at the confluence of these 
two streams. Salmon eggs and fry buried in the gravels in this zone 
are covered with salt water during a substantial part of the incubation 
period. The intertidal zone at the confluence of Harris River-Indian 
Creek is composed of alluvial deposits of sand and gravel (fig. 16). 
Intertidal sections are frequently less stable than stream channels 
above high-tide level (9), and streambed material is easily molded 
and reworked by heavy fall and winter floods. The stream mapping pro- 
ject, discussed earlier in this report, revealed that a considerable 
amount of streambed material is shifted annually in this zone. 
Figure 16.--Intertidal zone at confluence 
of Harris River-Indian Creek, 
18/ Particles of gravel, sand, silt, and clay. 
19/ The intertidal zone is considered to be the stream sections between 
the lower low-tide and higher high-tide level (9). 
BMa5uce 
