Mount Bonnell is often described as the highest point in Austin, with the elevation at its peak about 775 feet (236 m) above mean sea level (AMSL).

He also took refuge in a Mount Bonnell cave to recover from "flux", but was missing so long his sweetheart eloped.

Before meeting and marrying George Sinks, chief clerk of the Post Office Department during the Republic years, she lived on West Pecan, present day 6th street, and later wrote "Our home was on the beaten track of the Indians into town from the pass of Mount Bonnell.

The knolls beyond the quarry branch were interspersed with timber, and sometimes though not often, we would see galloping past the open spaces beyond the blanketed Indian.

It was a sheltered road, never traveled at night by whites, so the Indians claimed right of way, and all full moons brought moccasin tracks in abundance".

The Indians "seized the children, mounted their horses and made off for the mountains going in the direction of Mt.

The Simpson girl was killed, but the boy survived and was later "traded off to some Indian traders, who returned him to his mother".

It is because the boy survived and was returned home that we know what happened after the posse lost the trail of the Indians on Mount Bonnell.

Bonnell forms part of the Balcones Fault Escarpment and these "balconies" were first described by Bernardo de Miranda in 1756.

[17] The lower Cretaceous Glen Rose Formation limestone outcrops to the west of the fault zone but is buried 1000 feet to the east.

Upper Cretaceous formations follow, starting with the Del Rio Clay, Buda Limestone, and then the Eagle Ford Group.

The Hammett and the lower portion of the Upper Glen Rose act as confining units (or aquitard) for the Middle Trinity Aquifer.