Attached are pictures of a maple tree trunk in my backyard; not sure if you can tell from these pictures, but the base of the trunk has several splits/cracks, some of which appear to be relatively deep, and some appear to have some sort of black tarry substance oozing from them. I've noticed no other signs of the tree being in poor health (not sure if this is b/c there are no such signs, or b/c I'm not knowledgeable enough to detect them). At any rate, just wondering if these pictures/this description are enough for someone to have a decent guess at what might be going on, and/or if there's any cause for concern here. Thanks in advance!