I know this is the most obvious possible way to start off, but: Ice Age: Continental Drift is no less than the third sequel to 2002's blandly pleasant Ice Age, and I cannot figure out why. Okay, so why is thunderingly obvious: because the movies are ridiculously profitable (the third entry in the franchise, Dawn of the Dinosaurs, has as of this writing the highest non-U.S. box office take of any animated film ever made, at $690 million and change - a record its sequel is likely going to beat), and it is in a sense the obligation of movie studio executives to keep making sequels to ridiculously profitable movies until they stop making money. The real mystery is why, exactly, the Ice Age films are so massively successful: even though we all hopefully figured out a long time ago that lots of truly shitty movies do huge business, there's still at least a vague semblance of a meritocracy, and the really big hits have some kind of X-factor that you can still identify, even if you don't personally like it. Take the Shrek films, the only other animated franchise ever to hit four entries: I have no use for any of them, but I understand the draw of their populist post-modern travesty of fairy tale motifs and broad scatological humor. But Ice Age, damn. They're so exaggeratedly flimsy and blank: vacuous fetch quests starring three Pleistocene animals voiced by actors who barely tried to hide their disinterest in the material the first time around and have not bothered about it since then, predicated on musty, ancient dramatic scenarios pitched squarely at the 8-and-under set, yet papered floor-to-ceiling with surprisingly bawdy double entendres that the 8-year-olds' parents are undoubtedly too bored to find funny. What about this seemingly can't-hit situation makes it the basis for one of the most durable movie franchises of the 21st Century, I do not even want to speculate; it is far, far too depressing.

No mystery about the why of, "why did the storytellers think this was compelling enough to be worthy of their time?" because they plainly didn't. Last time it was a lost world with dinosaurs (a concept so hoary and ill-executed that even one of the characters in Continental Drift makes fun of it); this time it's pirates. In a movie set some 20,000 years ago. Populated by talking animals. The mind would reel, if reeling didn't take too much energy that Continental Drift has stolen away. It is gratifying, anyway, that Ice Age has officially reached the "Mad Libs" phase of its development, for these corporate product kiddie films are invariably more fascinating - though by no means "better" - as they grow increasingly brazen in just juggling crazy nonsense to see what happens.

There is, admittedly, one lingering reason to enjoy the Ice Age franchise: the Scrat. The little saber-toothed squirrel rat locked in an eternal struggle to capture an unattainable acorn (a safely neutered version of the Wile E. Coyote-Road Runner or Sylvester-Tweety dynamic for a franchise that's had a hell of a time reconciling the fact that one-third of its central cast is a natural predator of another third), who manic adventures in Tex Avery territory are the five or six minutes in every one of these features that genuinely and ecstatically works; the Scrat material in Continental Drift is perhaps the weakest in the franchise, and it helps not at all that the majority of it was excerpted in two short films that have come out in the last year and a half. But the last big Scrat scene is a charmingly warped little bit of what-the-fuckery, anchored by a fantastic surprise vocal cameo. I will not spoil it; but it is not worth the price of a ticket. It is, however, worth renting the film when you can fast forward through all the dreadful plot bits. My last hope at this point is that if they're going to keep making Ice Age - and now that they've managed to spin a half a movie's worth of plot into four features, I cannot imagine why they'd stop any time soon - eventually, around Ice Age 15 or so, all of those five-minute Scrat chunks will be enough to edit into a complete Scrat feature.

That glorious day being decades into the future, what shall we make of Continental Drift? That it exists; that it isn't nearly as fun in its genre-mashing adventure as the marginally rousing Dawn of the Dinosaurs, but that it's also less grating than the truly hideous first sequel, The Meltdown, and that Blue Sky Studios isn't as good as DreamWorks Animation is at pointless, distracting celebrity voice casting: joining Ray Romano the Mammoth, Dennis Leary as the Indignified Saber-Tooth Tiger (that Leary is voicing, in a crushingly mediocre family flick, a predator stripped of his ability to be savage, simply must be a conscious meta-joke by now), John Leguizamo as the Idiot Lisping Sloth, Queen Latifah the Lady Mammoth, and Seann William Scott as the Loathesomely Dumb Opossum, we now get to add Keke Palmer as the Rebellious Mammoth Teen Daughter, Wanda Sykes as the Senile Grandmother Sloth (after the previously mentioned cameo, hers is the only performance worth a damn), Peter Dinklage as the Simian Pirate Captain who is performed in far too genuinely brutal a register for such a flaccid kids' movie, and Nicki Minaj as the Character Who Serves No Narrative Purpose Other Than To Facilitate Casting Nicki Minaj, Who, We Find, Is an Epically Poor Actress, So Thank God She's Barely Present.

There is a plot in all that: in the opening, Scrat causes the continent of Pangaea to split into the continents we now know (scientific accuracy not being a terribly signifiant concern in this franchise, I'm still a little impressed by how aggressively Continental Drift manages to violate even the most rudimentary, grammar school-level understanding of plate tectonics), and the ensuing cataclysms, cause Romano-Mammoth to be separated from his family just after a terrible fight between he and Palmer-Mammoth. He and Leary-Tiger and Leguizamo-Sloth encounter pirates on a iceberg shaped exactly like an 18th Century tall ship (one of no fewer than three such objects introduced into the film by Dame Contrivance, on the logic of in for a penny of unlikely anachronistic pirate ships, in for a pound, I guess). These pirates chase the three heroes all the way to someplace that isn't home and then back home, where they are defeated by the power of Mammoth Nuclear Family Love. Also, there are some really obvious, really cheesy 3-D effects, and this is something I support: immersive landscapes are fine and all, but sometimes you just want to see something immensely stupid and proud of it, and that is where I largely reside in respect to 3-D.

If you are of an age to care enough about movies that you read movie reviews, you are not the film's target audience. You are perhaps the parent of a such a person, or morbidly curious, or you found the earlier films blandly unobjectionable and you were looking forward to more of the same. If it is the last of these, I have good news for you. For everyone else, it is what it is, a pointlessly random collection of talking animals who do things that are not funny and have character revelations that do not rise above the level of a sitcom episode stretched out (though only a little; Continental Drift, at 87 minutes, at least has the merit of being sleek and fast-moving), and at this point, thinking of each new Ice Age picture as a sitcom episode is just about right. Will the kids love it? I honestly don't care, though I pity them if they do. Once upon a time, we had children's movies that could be revisited years later with affection and no real sense of shame, and that is the kind of thing that I'd prefer my guileless family entertainment to be. The 8-year-olds of today will not be sharing Continental Drift with their 8-year-old children of tomorrow; and if they do, then our culture is worse off than I'd be inclined to guess in even my most pessimistic moments.