As we drive south we are on the Packsaddle Schist with occasional outcrops of granite and then we enter a terrain of Valley Spring Gneiss north of the F .M. 965 junction. Watch for low roadcuts where the light-colored gneiss looks like contorted, banded granite, whereas the schist is black and has platy minerals that sparkle in the sunlight.
Looking east from the junction of Texas 16 and F.M. 965 the skyline hills are a block of Paleozoic sedimentary rocks, which occupy a graben that was dropped into the Precambrian rocks at the southeast comer of the Llano uplift. The Paleozoic sedimentary rocks were actually more resistant to weathering than most of the surrounding Precambrian crystalline rocks, so they stand elevated here as a
ridge line.
North of Echert, hills scattered with pink, blocky boulders of gneiss, and granite seen from the highway are part of the central Precambrian portion of the Llano uplift.
Look west to see the topographic edge of the Edwards Plateau, where the Cretaceous sandstone and limestone form a distinct cliff
The road ascends from the Llano basin proper climbing through a short segment of Hensell sand. Watch carefully for brown sandstone roadcuts for about a mile on either side of the small hamlet of Echert. This is Cambrian Hickory sandstone preserved in a faulted, down-dropped block on the edge of the Llano uplift.
North of Fredericksburg, Texas 16 traverses Cretaceous rocks, crossing about eight miles of poorly exposed, flat-lying, thin beds of tan-colored Hensell sand seen in hills on either side of the road.
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mile 0.0 (30o 45.590; 98o 40.510) - Junction of 29, 16, 71
Llano River Bridge. Llano was built on the Spring Valley Gneiss which can be seen at many sites in the town and at the river.
mile 1.4 - 30.4 (30o 44.285; 98o 40.593) - highway 71 departs to the east; this is the route of the Llano to Marble Falls trip
mile 1.6 (30o 44.131; 98o 40.698) - highway 2323 departs to the southwest; this is the route of the Llano to Fredricksburg highway 2323 trip
Pass low roadcuts where the light-colored gneiss looks like contorted, banded granite, whereas the schist is black and has platy minerals that sparkle in the sunlight
mile 3.4 (30o 42.601; 98o 41.010) - Fine-grained granite exposed in creek bed (Oatman Creek).
mile 4.2 (30o 41.890; 98o 41.091) - boulders left side - Packsaddle Schist (preCambrian)
mile 4.3 (30o 41.812; 98o 41.113) - boulders right side - Packsaddle Schist
mile 5.1 (30o 41.159; 98o 41.174) - The hill on the right distant is Packsaddle Schist
mile 8.2 (30o 38.583; 98o 42.156) - The hill on the right behind the house is Packsaddle Schist
mile 10.2 (30o 37.081; 98o 42.279) - Crest of hill and road cut. This is atypical Cambrian Hickory Sandstone , lighter in color and more color banded than most of the unit. The rocks are part of a graben (downfaulted block) and many small faults cut the road cut. Small faults called deformation bands are common at this location. The outcrop on the right side of the road is Valley Spring Gneiss (preCambrian)
South of this narrow band of sedimentary rocks, we are driving through Valley Springs Gneiss.
This hill seems to be another watershed boundary. North of the hill, creeks flow into the Llano River before getting to the Colorado River, south of it creeks drain into Sandy Creek and then into the Colorado River.
mile 10.8 (30o 36.407; 98o 42.208) - gneiss outcrop on right
mile 11.2 (30o 36.325; 98o 42.212) - "Town" of Oxford. Cemetery population outstrips living population.
mile 12.5 (30o 34.979; 98o 42.123) - Valley Spring Gneiss outcrop on the left.
mile 14.6 (30o 33.136; 98o 42.093) - Sandy Creek. Note the large amount of, well, sand, in the creek. A sand and gravel pit is operating on the west side. Just before the creek we pass from the Spring Valley Gneiss to a narrow band of the Packsaddle Schist and then into the Legion Creek Granite. The topography changes as we move into a five-mile exposure of granite rock.
mile 15.3 (30o 32.575; 98o 42.269) - highway 965 to Enchanted Rock departs to the southwest. The Enchanted Rock trip is from Fredricksburg to Enchanted Rock Park, then to this intersection.
mile 17.0 (30o 31.142; 98o 42.441) - blocky boulders of granite on both sides continues to mile 20. Mica and quartz minerals in the granite give a glitter to these rocks that you do not see in the metamorphic gneisses and schists.
mile 18.8 (30o 29.592; 98o 42.274) - hill to right is Packsaddle Schist
mile 19.2 (30o 29.227; 98o 42.234) - boulders
mile 19.6 (30o 28.830; 98o 42.295) - granite in creek and roadside
mile 20.3 (30o 28.442; 98o 42.733) - we are passing out of the exposure of granite rocks and into the Packsaddle Schist which continues to mile 21
The geology between mile 24 and 28 is dominated by faulting that brings faulted Cambrian rocks to be exposed. The highway corsses several of these faults, but outcrops cannot be seen
mile 25.1 (30o 24.815; 98o 44.208) - Eckert
mile 30.0 (30o 21.328; 98o 46.735) - the outcrop on the right is Hensell Sandstone
mile 30.7 (30o 20.861; 98o 47.061) - Hensell Sandstone on left forming cliff
mile 38.1 (30o 16.442; 98o 52.229) - the intersection of hwy 16 with highway 290-87 in Fredericksburg
If you want to return to Llano by ranch road 965, turn right onto 290-87 and continue several blocks to the right turn for 965