Band spectra from Columbia Light and South Pass (Figs. 19 to 29) are quite 

 similar in shape and peak frequency. They are consistent with the standard 

 concept of a smooth, continuous spectrum. However, the significant differ- 

 ences in modulation time scale between the Columbia Light and South Pass 

 records cannot be identified in the smooth spectral curves. Thus, hypoth- 

 esis (a) must be true, which is that spectral components are sometimes 

 discrete and are not smeared over a broad, continuous spectrum. 



It was noted earlier that wave grouping characteristics change over 10- 

 minute intervals in some of the field records. The changes include the 

 appearance and disappearance of noticeable groupings as well as in one case, 

 a large change in modulation time scale. The MRS analyses provide definitive 

 data for comparing the structure of successive time-series records. 



The procedure used for comparison was to match prominent constituents in 

 each of the records used in estimating Tj^j^g values (Figs. 16 to 19, 22, 23, 

 and 25 to 28) with constituents in records immediately preceding or following. 

 Constituents for which the frequencies were within about 0.001 hertz of each 

 other were considered matched. Thus, the 1300- to 1308.5-hour and 1308.5- 

 to 1317-hour Columbia Light analyses (Figs. 19 and 20) were compared. Con- 

 stituents were identified in the second record at about the same frequencies 

 as the three prominent constituents in the first record, and vice versa. 

 Similarly, the Columbia Light MRS analyses in Figures 22 and 23 were compared 

 and matched constituents were identified when they occurred. The South 

 Haven and South Pass MRS analyses were also compared. Most of the prominent 

 constituents could be matched with constituents in preceding or following 

 records. However, the matching constituent is often much lower in amplitude. 



It is expected that all the field records contain independent frequency 

 constituents. However, it is also anticipated that they contain some noninde- 

 pendent constituents which are bound together and are nondispersive. Although 

 both bound and free constituents may be represented in Figures 16 to 29, the 

 process used to select the records and constituents used in estimating Tw^c 

 values has favored those constituents which contribute to wave grouping. It 

 is suggested that these constituents are nonindependent . 



Phases from MRS analysis associated with constituents matched between 

 records, as discussed above, are plotted in Figure 44. Although the phase of 

 each constituent clearly varies between records, there is a strong indication 

 that phases of the constituents relative to each other do not vary between 

 records. In fact, there is evidence in the figure that the relative phases 

 of constituents with similar frequency at South Pass do not vary during the 

 entire 60-minute recording interval. A step further, comparing constituents 

 in the 1300- to 1308.5-hour and the 1508.5- to 1517-hour Columbia Light 

 analyses, reveals additional constituent matches. Relative phases for these 

 constituents from records a full 2 hours apart show an amazing consistency 

 (Fig. 45). Phases for matched constituents from the 1308.5- to 1317-hour 

 analysis are also reasonably consistent, as shown in the figure. The same 

 conclusion is reached from a comparison of relative phase for frequency- 

 matched constituents in the first and last South Haven and South Pass records 

 (Figs. 46 and 47). Since, by chance, the first and last South Pass records 

 were not well grouped, phases for constituents in the 1510- to 1520-hour 

 record which matched constituents in the other two records are also plotted 

 to give further credence to the pattern. This evidence strongly supports the 

 hypothesis that frequency components are sometimes related in a deterministic, 

 nonrandom way (hypothesis b) . 



65 



