I came across this question while studying in my text book: What does the existence of strata containing a reverse fault and above them parallel strata refer to? I thought that referred to an angular unconformity, thinking that the fault should make a tilt in the layers, and that the tilts which appear in angular unconformity happen by a fault or a fold, but I found that the answer is "disconformity", so I became confused. Would that reverse fault present only a crack not a tilt? Or was the strata where the fault appeared was parallel so the movement didn't affect the angle of the layers? Would the tilt which appears in angular unconformities happens by other factors more than a fault and a fold?. I would like anyone to help me understand this, because I didn't get help searching in many websites but some definitions and concepts which made me more perplexed.

  • $\begingroup$ It would be very helpful if you could make a sketch of your explanation and add it to the question. $\endgroup$ – bon Oct 21 '16 at 12:12
  • $\begingroup$ It depends on the local circumstances. A reverse fault can locally tilt the strata, on both sides of the fault, but that is not what is normally referred to as an angular unconformity. This kind of stress feature isn't a disconformity either. A disconformity results from a time-break in superposition, without an appreciable angular unconformity. So it is the parallel superposition of pre- and post-tectonic strata that is the disconformity, not the locally deformed tilting at the fault plane. $\endgroup$ – Gordon Stanger Oct 23 '16 at 0:34

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