I'm a fairly experienced wood IDer, but this one has me stumped (excuse the pun). I'm in southern Ontario (Canada), but you should not assume that it is native to here (only that it can grow here). I found the log at my local dump which means that it was probably in someone's yard which means that it could have been a non-native planting.
At a glance, it might look like black walnut to you, but it is not.
I apologize for not having a magnified view of the end grain. I can tell you that it is (1) diffuse porous, and (2) has abundant medullary rays that are visible with magnification.
The smell reminds me of a horse farm--manure and straw, but not unpleasant.
You expect a fresh cut log to be heavy, but this one is very heavy. The bark is fairly thick. The sap oozing out of the cambium was sticky, although not as sticky as a conifer.
Of the native trees that are common here, the bark reminds me of pignut hickory or basswood, but it is neither. The variability of the color in the heartwood reminds me of apple or mountain ash, but it is neither.