• 1 



> 

 o 

 n 



1 1 



E. 



c 



8 o 



CO 



> 



UJ n 



3.0 

 2.5 

 2.0 



5 

 

 5 

 



-0.5 



-1.0 





N I I I I 



\ Higher High Tide 







High< 



1 



it High Tide s 















Lower High Tide 

























/ 





























1 







\ / 

























Higher Low Tide 







































Mean Lower Low Water (MLLW) 



► 





































L 



ower 



Low 1 



ride 



















2 4 6 8 10 12 14 16 18 20 22 24 26 28 



Hours 



Figure 1 1 . Typical tide curve for Oregon coast. Based on 6 years of observations in 

 Yaquina Bay. By definition, mllw is zero 



expanded geodetic network. The reference zero point of IGLD 1985 is 

 located at Rimouski, Quebec (Figure 12). The new 1985 datum establishes a 

 set of elevations consistent with one another for surveys taken within the time 

 span 1982 - 1988. IGLD 1985 is referred to the North American Vertical 

 Datum (NAVD) 1988. Note that the IGLD's are not parallel to NGVD 29 or 

 NAVD 1988 because the Great Lakes datums are dynamic or geopotential 

 heights and are designed to best represent the hydraulic structure of the lakes 

 and connecting waterways (Great Lakes Commission 1986, HQUSACE 1991). 



Geologic and Sediment Data 



It is often important in studies of the geologic and geomorphic history of 

 coasts to evaluate existing geologic and sediment data. This type of informa- 

 tion is dispersed among numerous agencies and sources and includes a variety 

 of materials such as geologic maps, soil surveys, highway borings, and pro- 

 cess data such as the concentrations and fluxes of suspended sediment from 

 nearby rivers. Differences in geology and soil type may provide clues toward 

 understanding erosion and accretion patterns. Geologic and sedimentologic 



Chapter 2 Secondary Sources of Coastal Information 



19 



