My 4-year-old son is very into earthquakes and volcanos. Always on the lookout for crossword theme, I was idly counting letters in the book we were reading and was excited to discover that SAN ANDREAS FAULT was 15 letters. It wasn't long after that that this radical theme occurred to me. I'll leave it to the reader's imagination how the puzzle was constructed (hint: it wasn't too bad).

Because the theme affects so much of the puzzle, I tried to make both the entries and cluing easier than you would expect for a Thursday. I expect I undershot the mark, and Will has made some of the clues more difficult.

Of my three main test-solvers for the Times crosswords, one "loved" this puzzle and two "hated" it. No one was lukewarm about it! Mindful of possible negative reactions, I eased up a few of the Down clues in the ninth column, to make the gimmick easier to see. I hope these changes bring a few more solvers into the fold. Notice the one-letter answer (T) at 65A — a first, as far as I can remember.

The day to day administration of XWord Info has affected my solving experience in strange and unexpected ways. One of the aspects that's changed the most is regarding "trick" puzzles. Jim and I want to keep the database as clean and useful as possible (we fix up all the screwy answers), so every time we get something like today's, I either appreciate the trick even more as I perform the fix-ups, or grumble as I wade through C# coding syntax. Ah, the highs and lows.

I liked the concept today. I generally try not to link to old puzzles (because I don't need to remind people that most everything has been done in some way or another) but this one so heavily reminded me of Andrea Carla Michaels's very first NYT publication, taken to a new level of difficulty. I was a little frustrated as I was solving, but the trick seemed pretty neat once I cottoned to it (the entire right half of the puzzle "slipped" down one row). And who doesn't like seeing ATMSBROAD in the puzzle? Don't answer that. And don't worry, we fixed up that entry in the database.

I would have loved perhaps one or two more theme answers. It's pretty neat that the SAN ANDREAS FAULT is a "site of slippage" and BANANA PEEL / PATCH OF ICE fit the theme (and they intersect SAN ANDREAS FAULT!), but it felt slightly thin to me. It could have been really fun to open it up to other meanings of "slip", like giving someone the slip or a slip of the tongue. Even one more theme entry would have been enough for me.

There's some really nice stuff in the fill, especially PEACH FUZZ and MACH ONE. SUBDIVIDE isn't that snazzy in itself, but the clue did a great job in making it a strong entry. Overall though, with just three them entries, I would have liked more long, snappy fill. Yes, the theme entries intersecting makes it harder to work in good fill, but not that much harder. I would have liked to have seen more 7+ letter fill, even if that meant having more 3-letter fill in exchange. There's so much in the 4-, 5- and 6-letter range today, and any fill under seven letters is hard to make memorable. (You can press the "Analyze" button at the bottom of the page to get the exact distribution.)

Overall, nice concept with some unfulfilled potential.

Yes, this is the first puzzle in our database with a one-letter answer. A couple of puzzles have two-letter answers: this 2008 icing-around-the-outside grid by Joe Krozel has eight of them, Patrick Merrell's famous Mistakes puzzle from 2004 has two, and Henry Hook's puzzle from the same year has one.