The 2007 Mother Lode Roundup will hit its stride Thursday night, when local calf-scramble teams go on the block at the Tuolumne County Sheriff's Posse's annual Calcutta.

Calcutta organizer Ty Wivell has his usual advice for anyone brash or bold enough to enter the 7 p.m. bidding wars at the Posse's Rawhide Road headquarters: "Your heart will be pounding big time."

And your wallet may be shrinking big time: Collectively, Calcutta bidders regularly pony up more than $10,000 for their favorite scramblers.

A "social hour," during which players can build their courage, will begin at 6 p.m.

Here's how the Calcutta works:

At the stroke of 7, Roundup Queen Katie May Broderick and her court will parade each of the 20 local calf-scramble teams over the stage for inspection by would-be buyers.

Bidding action should be spirited. A crowd of more than 200 is expected and in the past top teams have gone for as high as $1,500.

The scramble is an event in which two cowboys (or a cowboy and a cowgirl) run down and tackle a galloping calf. One then ties a ribbon to its tail and sprints over the finish line.

The local teams will compete simultaneously in the Saturday and Sunday Mother Lode Roundup rodeo sessions. Teams with the three fastest times over the two days will win skillet-sized belt buckles.

But for Calcutta participants, cold cash is at stake.

Calcutta bidders canny or lucky enough to buy one of the top three teams will split a bid pot that in the past has been as high as $13,000.

Here's the Calcutta formula: After bids on all 20 teams are in, 25 percent of the total is raked off for the posse's scholarship fund. Of the remainder, half goes to buyers of the winning team, 30 percent to the runners up and 20 percent to third-place title holders.

This year's calf-scramble lineup:

Saturday Tanner Neal and Chris Peterson, Jason Wood and James Smith, Jacob Reed and Scott Mittry, Kyle Tomasovich and Glenn Gray, Cody Munsel and Tim Bagen, Jake Harper and Melissa Webbon, Morgan Hastings and Jamie Smith, Matt Hon and Preston Leslie, Jessica Durnall and Spencer Boire, Kyle Willis and Chance Inwood.

Sunday Chris Labriola and Joel Thompson, Lucas Van Bolt and Brandon Lemons, Cody Munsel and Ren Gianninni, Chris Amaro and Jake Harper, Michal Suess and Joel Franco, Rigo Estrella and Cody Casner, Jesse Underwood and Tyler Brescia, Dalton Lyons and Kendra Brennan, Joe Opie and Garret Dennis, Damian Uribe Sundborg and Gilbert Uribe.

Admission to the Calcutta is free. Hors d'oeuvres and a no-host bar are featured.