M A S T E R P A G E
Sag Pond, 1830 to 1994
2.3d
Right Lateral Strike-Slip Fault
Left Lateral Strike-Slip Fault
Figure 1, Sag pond
In the left-hand side of Figure 1 (X), there is a place where the ground has pulled apart. The depression caused by
this “pull-apart” basin is called a sag pond. This is a very narrow, long or elongated pond or basin. Sag ponds are
generally aligned with the long axis parallel to the faults. In the right-hand drawing, (Y), a ridge is being formed
by squeezing, or compression.
Figure 2, Sag pond 1830
Fault slippage has formed a sag pond, which has filled with water containing reeds, cattails, and algae. These
organic materials die and accumulate rapidly on the bottom of the sag pond in the form of peat. Peat can
accumulate as much as several centimeters per year.
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