By Sam Laskaris Writer The Six Nations Rivermen continue to sit atop their league standings after splitting a pair of weekend matches. But the local Senior B squad has plenty of company as squads jockey for positioning near the top of the Ontario Series Lacrosse (OSL). The Rivermen, the defending OSL champions, have 15 points courtesy of their 7-2-1 mark. Six Nations defeated the visiting Owen Sound North Stars 11-6 this past Saturday in a match held at the Six Nations Sports and Cultural Memorial Centre. But the Rivermen were then downed 13-7 by the host Oakville Rock on Sunday. That contest was at the Toronto Rock Athletic Centre in Oakville. With the victory Oakville is right on Six Nations’ heels now with 14 points. The 7-1-0 Rock have played…