Black dirt or sticky wet clay?

I'm building up a pad for a new house the front of the house needs 1' of fill and the back needs 2' to 3' of fill. Problem is I there is no good clay anywhere on the property. On the property there is an old lagoon I've been taking the burms down with the scraper and hauling it in the full areas around the house and its nothing but black dirt but it has good moisture. Once you get past the 3' of black dirt it turns to a wet sticky blueish grey clay. I Need help cause I'm not sure what to do? Use the black dirt fill that has good moisture or the sticky wet clay? Any info is much help!

Black dirt or sticky wet clay?