Help with large oak

[StilLrnin]

1st...like to say I've learned a lot here & want to give a big thanks to everyone here !!!

I have several large "Valley Oaks" around my house (N. California), one of which has a large limb that hangs over a parking area and pathway, that worries me.
It is about 20' feet up and goes out over 20'. It starts at a junction about 14' up or so. (see pic)
The tree itself is over 120" in circumference and probably 100+ yrs old.

I have been seeing a black substance on the ground but didn't notice until recently that it is dripping from a scar on the above limb. Closer inspection I see that small scars are starting on the opposite side of the same limb too.

My question, is this the way a large oak breaks a limb?
Or is the tree holding it's own & repairing a break that started? (not much hope of that, I know!)

I have trimmed back about as much as I can to reduce the weight without affecting health. On one branch cut, about 15' up from the crack/scar, I notice "black" in the center (still solid wood, just black)...

Does this mean the center is rotting & thats the reason for the crack/scar?

I'll try to attach a few pics....

 

[StilLrnin]

A few more pics...

 

[treeseer]

They look like cracks from excessive movement. When the adjacent trees were cleared, this one lost its shelter from the storms. Perhaps a candidate for cabling. Considering the size and value of that tree, you need a certified arborist on site to work with it.

 

[StilLrnin]

They look like cracks from excessive movement. When the adjacent trees were cleared, this one lost its shelter from the storms. Perhaps a candidate for cabling. Considering the size and value of that tree, you need a certified arborist on site to work with it.

No recent changes (in the last 20 years...) but a few quakes! Just had a 4.5 & I noticed the small crack/scar... but maybe was already there.

There is a "Bartletts" arborist in the area, I'll give him a call.

Just wondering if the "black" in the wood that far out on the limb means the whole limb is shot or not... this is a limb we will be walking under so I can't take chances...
Love that tree tho! Hope it dosen't have to come down!

 

[treeseer]

Just wondering if the "black" in the wood that far out on the limb means the whole limb is shot or not... !

Discoloration is not decay. Let us know what the arborist says and does ok?