Question: What further acellerated the uplift of the Sierra?
About the article "Yosemite National Park", section "Uplift and erosion".

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Starting 10 million years ago, vertical movement along the Sierra fault started to uplift the Sierra Nevada.
Subsequent tilting of the Sierra block and the resulting accelerated uplift of the Sierra Nevada increased the gradient of western-flowing streams.
The streams consequently ran faster and thus cut their valleys more quickly.
Additional uplift occurred when major faults developed to the east, especially the creation of Owens Valley from Basin and Range-associated extensional forces.
Uplift of the Sierra accelerated again about two million years ago during the Pleistocene.
The uplifting and increased erosion exposed granitic rocks in the area to surface pressures, resulting in exfoliation (responsible for the rounded shape of the many domes in the park) and mass wasting following the numerous fracture joint planes (cracks; especially vertical ones) in the now solidified plutons.
Pleistocene glaciers further accelerated this process and the larger ones transported the resulting talus and till from valley floors.
Numerous vertical joint planes controlled where and how fast erosion took place.
Most of these long, linear and very deep cracks trend northeast or northwest and form parallel, often regularly spaced sets.
They were created by uplift-associated pressure release and by the unloading of overlying rock via erosion.
This is a list of Sierra Nevada topics, about the Sierra Nevada of California, USA.
Please see Sierra Nevada for alternative meanings.
"See also:" Bibliography of the Sierra Nevada (U.S.) for further reading. 
  The Kingdom of Koya, a pre-colonial African state in what is now northern Sierra Leone  Koya, Sierra Leone, a village in Sierra Leone  
10 million years ago, vertical movement along the Sierra fault started to uplift the Sierra Nevada.
Subsequent tilting of the Sierra block and the resulting accelerated uplift of the Sierra Nevada increased the gradient of western-flowing streams.
The streams consequently ran faster and thus cut their valleys more quickly.
Tributary streams ran more-or-less in line with the Sierras, therefore not having their gradients increased.
Thus their rate of valley cutting was not significantly affected.
The results were hanging valleys and cascading waterfalls where the tributaries met the main streams.
Additional uplift occurred when major faults developed to the east, especially the creation of Owens Valley from Basin and Range-associated extensional forces.
Uplift of the Sierra accelerated again about two million years ago during the Pleistocene.
However, Yosemite valley was not created by streams or fault lines (to create a graben valley), such was suggested by geologist Josiah Whitney.
Glaciers shaped the Yosemite Valley, and can easily be confused with a graben valley.
(Example of a graben valley is Death Valley in California)The uplifting and increased erosion exposed granitic rocks in the area to surface pressures, resulting in exfoliation (responsible for the rounded shape of the many granite domes in the park) and mass wasting following the numerous fracture joint planes (cracks; especially vertical ones) in the now solidified plutons.
Pleistocene glaciers further accelerated this process and the larger ones transported the resulting talus and till from valley floors.
Numerous vertical joint planes controlled where and how fast erosion took place.
Most of these long, linear and very deep cracks trend northeast or northwest and form parallel, often regularly spaced sets.
They were created by uplift-associated pressure release and by the unloading of overlying rock via erosion.
The great majority of Yosemite Valley's widening, for example, was due to joint-controlled rockfall.
In fact, only 10% of its widening and 12% of its excavation are thought to be the result of glaciation ("Yosemite: A Visitors Companion", pgs 75-76).
Large, relatively unjointed volumes of granite form domes such as Half Dome and monoliths like the 3604 feet (1098 m) high El Capitan.
Closely spaced joints lead to the creation of columns, pillers, and pinnacles such as Washington Column, Cathedral Spires, and Split Pinnacle. 
Geologic Province: Black Mesa Basin* Great Basin province* Geen River Basin* Ghost Ranch* Las Vegas-Raton Basin* Orogrande Basin Palo Duro Basin* Paradox Basin* Permian Basin Piceance Basin* Plateau sedimentary province* San Juan Basin* Sierra Grande Uplift* Uinta Basin* Uinta Uplift* Wasatch Uplift* Parklands (incomplete list): Canyonlands National Park - see geology of the Canyonlands area Capitol Reef National Park - see geology of the Capitol Reef area Glen Canyon National Recreation Area - see geology of the Glen Canyon area Petrified Forest National Park - see geology of the Petrified Forest area Zion National Park - see geology of the Zion and Kolob canyons area