Domestic box office expectations for “Ice Age: Continental Drift” are just the tip of the prehistoric iceberg for the fourth installment of the Fox franchise.

The series has a mammoth-sized following overseas, but domestic B.O. projections vary widely for the weekend. On the low side, Fox is anticipating three-day grosses in the high-$30 millions, which would be the lowest domestic bow yet for the toon franchise. More optimistic bizzers, meanwhile, expect the toon to reach at least $50 million through Sunday.

The biggest reason for Fox’s modest prediction is stiff competition from “Madagascar 3” and “Brave,” still playing solidly. But otherwise the field is wide open: There aren’t any other domestic wide releases bowing this weekend.

“Continental Drift” is already sitting pretty financially thanks to an overseas cume approaching $240 million as of Wednesday.

The “Ice Age” franchise’s second installment, “The Meltdown,” saw the biggest three-day Stateside opening for the series, with $68 million in 2006. Third pic “Dawn of the Dinosaurs,” opened midweek in2009 and in six days collected $66.7 million, of which nearly $42 million came during the weekend. The first pic debuted at $46 million in 2002.

None of those films managed to cross $200 million domestically; “Dawn of the Dinosaurs,” however, is the all-time biggest-grossing toon internationally with $694 million.

Given the franchise’s overseas popularity, Fox launched the toon two weeks ago throughout Europe and Latin America. The studio aims to give “Continental Drift” a longer summer playtime in those regions, since Germany and Mexico are the franchise’s highest-grossing territories.

Bizzers say it’s unlikely “Continental Drift” will exceed its predecessor’s domestic cume, the franchise’s best-yet Stateside tally at $196.6 million.

Still, domestic playability for “Continental Drift” depends greatly on just how big the pic starts out this weekend, since it reps the last major studio toon to bow this summer. Focus Features’ stop-motion toon “ParaNorman” launches Aug. 17.

Unlike mega-grossing animation franchises like “Shrek” and “Toy Story,” Fox’s “Ice Age” series has struggled to develop auds beyond kids in the States. That could greatly affect 3D percentages for the new “Ice Age”; pic screens in the format in 2,731 locations, or 70% of its total count. What’s more, 3D has been leveling off recently, especially with “Brave” and “The Amazing Spider-Man.”

As to the weekend’s holdovers, “Spider-Man” should drop 45%-50% — a solid hold that would yield a weekend gross in the low-to-mid $30 millions. The superhero pic already crossed the $400 million global mark, of which nearly $160 million has come Stateside.

Also holding well, Universal’s R-rated pair “Ted” and “Savages” have cumed $133 million and $21 million, respectively. Both pics have played well with adult auds during midweeks.

And at the specialty B.O., IFC launches Michael Winterbottom’s “Trishna” at two locations in New York and one in L.A. The Weinstein Co.’s Swedish crime drama “Easy Money” bows this weekend at two Stateside locations, as does Millennium Entertainment’s psychological thriller “Red Lights.”