It is a poorly understood western "outlier" of the ~93-85-Ma Tuolumne Intrusive Suite of the Sierra Nevada batholith.

On the west end of Yosemite Valley, it is more homogeneous and light-colored, and on the east, it is more streaky, with an uneven composition.

The hornblende is tabular, of crystals which are usually 4 - 6 millimeters long, and helps to define a weak to moderately strong magmatic foliation and lineation.

Plagioclase makes up about 50% of Sentinel Granodiorite, and in size, ranges from one to ten millimeters.

Interstitial potassium feldspar makes up ten to thirty percent of Sentinel Granodiorite, is two to five millimeters across.

[1][3][8] The rock forms part of a large irregular intrusive body, but the portion of it here considered is a belt about 2 miles broad that crosses the valley from north to south.

[4] In rock climbing, Sentinel Granodiorite is noted for its dihedrals,[9] plus for having dikes.