datingfor 40plus com - Radioactive dating sedimentary rock

Pilot Knob is one of around 75 late-Cretaceous Period volcanic complexes scattered around Central Texas from Waco to Austin, San Antonio, and Del Rio.

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The beach rock is now known as the Mc Kown Formation of the Austin Chalk.

Because the volcanism at Pilot Knob occurred during the deposition of the Dessau and Burditt Formations, an age of Lower Campanian (83 to 79 million years BP) can be interpreted for the volcanism according to the ages of the formations in the Austin Chalk, correlated to radiometric dated sections in the Rocky Mountain Region.

It appears along Onion Creek, where it is responsible for both Upper and Lower Mc Kinney Falls.

The entire shelf continued to subside after volcanic activity ceased, and muds of the Taylor Group gradually covered the entire volcano.

As volcanic activity diminished, beaches developed around the volcano.

One such beach deposit, now lithified and resistant to erosion, extends several miles to the north of the volcano.

The volcano at Pilot Knob exerted a profound influence on the stratigraphy of the Upper Cretaceous sedimentary rocks of the Austin area.

The volcanism occurred during the deposition of the upper part of the Dessau and the Burditt formations of the Austin Chalk.

The subaerial Pilot Knob ash cone allowed the intrusion of magma into the mound without contact with sea water, resulting in quieter lava eruptions.

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