Fished Kirwin today, North brush piles. About noon the Northern half of the lakes ice sheet broke loose and moved North due to the wind. The ice broke and had large cracks going out to the open water in the middle. Cracks would open up to 2 feet wide and come back together then open up again for the next 2 hours. I just was coming off when this happened and the remaining 7 guys made it off also without falling in. It was the most dangerous time in my ice fishing career ( I am 51). Prior to this event the ice was a rock solid 4 inches of excellent, hard ice. However, when it broke loose 4 inches of excellent, hard ice was irrellevent. I would NOT go back out unless there is a lot of very cold weather.