Pathfinder GM question. Create pit + wall of stone

Hey guys, I ran into an interesting, encounter issue in my game tonight.  I had the party fighting some "blast shadows", and they ended up killing them in a very cool way.  I am just worried because It feels kind of exploit-ish and as the GM, I am not sure how to logic it out or nerf it. Create pit + wall of stone. The wizard cast create pit around the 4 mobs, they all failed the save and fell to the bottom. the cleric then cast wall of stone covering the pit The wizard then "dispelled" his own pit Per the rules the pit slowly rises back to its original level.. well.. that pit was covered by a created stone wall... It is like hitting the "eye" of the star-gate.. instant squish ... your thoughts on this spell combo?  seems way to OP.. but not sure if it should work, or how to stop my players from abusing its power. Thanks Chuck G

not an issue really - just two spells that simulate a higher level ability. its powerful, uses to two high level spells, and is still not perfect. the mobs in the pit can dig enough of the edges out that they aren't instantly squished - it rises slowly after all - and ground is rarely even, so there could very well be ways out of the wall once the mob (even if just one or two) have managed to wriggle their way into the crevaces created by the uneven ground. another point of fact is that the dig spell is not a damaging spell, so while it refills, if the dirt has nowhere to go, it simply doesnt fill in the space that is occupied, leaving the mobs at the top of the pit, with possible breathing spaces and in whatever crevice is there at the top of the pit - remember the wall is supported by the surrounding land, which in most cases will not be truly flat.

This has been debated ad nauseam on the Paizo boards and there was never any consensus.  However, digging out is not an option since the pit is an extra-dimensional space.  My thought is this: In order to create a wall of stone across the pit the stone must be arched and buttressed so there should still be a space for the creatures to crawl out of.  Rationale: while the pit is only 10feet across it also has sloped  edges 5' around the pit making the effective area 20' wide. Thus, there must be some type of arch and buttressing.  Note: People have been quick to point out that my rationale doesn't work because the actual area is only 10x10. However, any effect like this is firmly in the GM fiat territory and thus this would be a reasonable compromise. A question? How did the wizard dispel a spell effect that he cannot see? You cannot target it if you cannot see it and the spell is not dismissable. Even Greater Dispel wouldn't work since it is a burst effect and the wall would block it.  - Gauss

I was thinking that create pit was flagged with the (d), but re-reading the spell I see that it is not dismissible.  That being said the duration of the pit was less than the duration of the stone wall, so the problem would still be true.  That being said, I really do like this logic you presented as it is spelled out  in the spell clearly "My thought is this: In order to create a wall of stone across the pit the stone must be arched and buttressed so there should still be a space for the creatures to crawl out of. "  It is the loop hole I need to prevent the abuse of a spell combo.  Those crafty players.. I tell ya, you never know what they will think of next.   Thank you everyone for your feedback on this. Chuck G

Or just make them acid blast shadows, and have em melt through the wall.  The problem with "exploiting" is that it's a double edged coin, exploiting your characters capabilities to make the best out a situation I see no issues with, but if they start doing shady shit like heavy meta gaming and quibbling about rulings they don't like because they came out on the losing end we start having issues.