EVANSTON—Northwestern completed the nonconference portion of its schedule with a perfect 4-0 mark Saturday by knocking off South Dakota, 38-7, at Ryan Field. The Wildcats did most of their damage on offense with the ground game, posting five rushing touchdowns and finishing with 277 yards on the ground.The five rushing scores were the most by a Northwestern team since Sept. 5, 2009, against Towson. Junior Venric Mark went over 100 yards on the ground for the second time this season, racking up 117 yards to go along with a career-best three touchdowns. Northwestern has now had an individual reach the 100-yard rushing plateau in three straight games, the longest such streak for NU since early in the 2007 season.Northwestern quarterbacks supported the cause by completing 12-of-15 passing attempts for 131 yards, keeping NU without an interception for the fourth time in four games this season.A 47-yard rush by Mark on the second play from scrimmage set the tone for the Wildcats, putting Northwestern down to the South Dakota 26-yard line. Mark would have the honor of finishing off the drive seven plays later with a 3-yard dive into the end zone for his second rushing score of the year.After a quick three-and-out by the Coyotes, Northwestern again found itself within scoring range thanks to a 42-yard catch-and-run from Trevor Siemian to Tony Jones. On the next play, Siemian handed off to senior Tyris Jones for a 5-yard rush to put the Wildcats ahead by two touchdowns midway through the period.South Dakota moved the ball as far as the NU 29-yard line on its next possession, but turned the ball over on downs after a fourth-and-15 stop by the Wildcats defense. Two possessions later, Northwestern took over with good field position after a short 17-yard punt by South Dakota. A dynamic 24-yard scamper by Kain Colter brought NU inside Coyote territory, and once again Mark moved the pile from six yards out to put the hosts ahead, 21-0.NU regained possession after an errant snap by the Coyotes was recovered by Brian Arnfelt, Arnfelt’s first fumble recovery this year to go along with two forced fumbles. Siemian directed the NU offense for the 28 yards to the end zone, ultimately handing off to Mark for his third score of the day.Northwestern’s fifth touchdown of the afternoon came on NU’s opening drive of the second half when sophomore Treyvon Green broke off a career-long 33-yard run up the middle of the line, capping a quick 71-yard Wildcats drive.Pat Fitzgerald and the Wildcats kept the action on the through the second half, eating up over nine minutes of clock time with a fourth-quarter drive that culminated in a 39-yard field goal by Steve Flaherty.Also on special teams, junior punter Brandon Williams shined with his 56.7-yard punting average on three attempts, including a 61-yarder that pinned the Coyotes on their own 1-yard line.Northwestern takes its undefeated record into Big Ten play next week, hosting Indiana at 11 a.m. Saturday in its 2012 conference-opener.