The pinkish areas along the bands and the rocks in the middle of the river are all granite.
I have heard that access to the area adjacent to Wirtz Dam has been shut off, perhaps only during Orange Alert, but maybe permanently.
South Side of spillway-
Access to this area may be eliminated due to construction, it's been a bunch of years since I've been out there.
How to get there-- Drive south on the road from Marble Falls to Horseshoe Bay. Look for a sign for an LCRA day use area. I think it also says "boat ramp". Drive into the day use area to the 2nd? parking area. Look for a gate in a chain link fence. Go through the door and down towards the river.
What to see: coarse-grained porphyritic granite with some interesting feldspar megacrysts, pegmatitic and aplitic dikes, xenoliths and enclaves, schlieren; also Paleozoic faults with oblique slip and several thick zones of fault gouge.
Where you turn off the road you are in Paleozoic rocks, a fairly significant fault (extinct) cuts through between the road and the dam.
small gouge zone showing probable sinistral offset
Closer to the dam wall, there are some larger zones of more coherent fault gouge that I do not completely understand.
Be careful if approaching the dam, the spillway does release water sometimes.
North Side of river: Similar stuff, less exposure. The south side is preferable but you really can't get from one to the other without a boat. Or some significantly wet pants.
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