. The Earth beneath the sea : History . â¢'^.I6± ..^ ± ± S. ^ + I I I \ I L a. a> E o o 00 80 60 40 20 0 20 40 60 80 100 120 Distance (km) Fig. 8. Travel-time plot of Capricorn Station C2. Layer 2 velocity = km/sec; Layer 3 velocity = km/sec; Layer 4 velocity = km/sec. (After Raitt, 1956.) 2. Layer 2 Surprisingly, the layer found at the base of the unconsolidated sediments, called Layer 2 for lack of a more descriptive name, has proved to be more difficult to measure than the deeper Layer 3 forming the main constituent of the crust. T
. The Earth beneath the sea : History . â¢'^.I6± ..^ ± ± S. ^ + I I I \ I L a. a> E o o 00 80 60 40 20 0 20 40 60 80 100 120 Distance (km) Fig. 8. Travel-time plot of Capricorn Station C2. Layer 2 velocity = km/sec; Layer 3 velocity = km/sec; Layer 4 velocity = km/sec. (After Raitt, 1956.) 2. Layer 2 Surprisingly, the layer found at the base of the unconsolidated sediments, called Layer 2 for lack of a more descriptive name, has proved to be more difficult to measure than the deeper Layer 3 forming the main constituent of the crust. The reasons lie mostly in the short distance over which it is observed as a first arrival. Furthermore, this distance is sensitive to variation in the thicknesses of Layer 1 and Layer 2. If Layer 1 were thicker than in the example of Fig. 1 or if Layer 2 were thinner, the distance over which Layer 2 brings in a first arrival would be shortened, and it would not require a drastic change to eliminate Layer 2 entirely as a first arrival. It is occasionally observed as a second arrival but interference with the refracted wave of Layer 3 usually makes this observation unreliable.
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Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectoceanbottom
