# Relative dating of intrusion

I am quite new to geology and have a realtive dating problem which I am a bit unsure of. I know very well the principle of superposition, principle of cross-cutting, etc., but am still a little bit unsure on one part. The problem is illustrated in the following picture:

My question is about the intrusion (E). Obviously the intrusion must have occurred later than the deposits of layers B, C and D, but how can I tell if the intrusion occurred before or after the deposit of layer A? In my opinon, both of these scenarios are possible. The intrusion does not appear to cross through A, so I suppose it is possible that A was deposited after the intrusion. But isn't it also possible that A was deposited before the intrusion, and the intrusion simply did not make it past layer B?

If anyone can let me know if there is any certain way of reasoning whether A or E occurred first, then I would greatly appreciate it.

• Indeed, you'd need additional information to tell which came first, A or E. – Daniel Griscom Jul 16 '16 at 20:09