Metal detecting on Dog Hill

I wasn't dressed like the fellow at the right. It was muddy, the ground still frozen, and not the best day to try to metal detect. But, I didn't fall down! I checked around the bottom of the hill. I found $1.07, a key, and 'Lucky's' Dog Tag. I got my pants, knee pad, gloves and ground cloth very muddy. I'll need to clean them up again. I couldn't believe how frozen the ground was. I thought it'd thawed out from the big January freeze, and I didn't think it would be frozen beyond the very top inch of the ground, which I then thought would've thawed out quickly each day. I was wrong. It was frozen down about 3 inches, almost as bad as the last time I tried to metal detect Dog Hill. About half the money I found was 'surface coins', detected by eye rather than the metal detector. I would think that if that much is lost on each sledding snow, the hill must be a good place to detect.