Four of the 40 soundings (see Figure 14) will be discussed in more 

 detail. The sounding plots are shown in Figure 15. The classification 

 of the sediment from these four soundings is shown in Figure 16. These 

 classifications agree reasonably well with classifications made on 

 vibracore samples. The first sounding (Figure 15a) was within an acous- 

 tically identified gas-charged sediment. Low strength sediments due to 

 gas charging may be more vulnerable to scour and storm-wave- induced 

 shearing stresses. The second (Figure 15b) was 0.6 miles west of the 

 first and just out of the gas-charged sediment area. The drops in cone 

 pressure seen in Figure 15a corresponded with gas-charged zones in the 

 sediment identified from vibracores. The slight difference between the 

 peak envelopes of cone pressure in Figures 15a and 15b may be a result 

 of somewhat lower effective stresses in the lighter gas-charged mate- 

 rial. The soundings shown in Figures 15c and 15d are from the Yukon 

 prodelta area. The Yukon prodelta contains sediment that is in the fine 

 sand to silt range which is often associated with liquefaction due to 

 cyclic loading on shore. Storm waves propagating northward from the 

 Bering Sea generate large cyclic bottom shearing stresses in Norton 

 Sound. This could result in liquefaction and movement of large sheets 

 of sediment within this area. The first sounding (Figure 15c) is from a 

 more protected area to the northwest and the second (Figure 15d) from an 

 area on the west side that is more exposed to intense storm activity. 

 It is apparent that the sediment in the protected area is not as dense 

 as the sediment in the exposed area (Figure 15d). 



,66° 



170 168 166 164 162 



Figure 14. Four of Norton Sound's sounding locations. 



24 



