Question

What caused the flatiron rock formations to tilt up and how long did this take?

Answer 1

Answer: This is because of tension

explanation: two tectonic plates of earths crust met and it caused enough tension and one tilted upwards. This prossess can take up to 100 million years.

Answer 2

The Flatirons are part of a rock unit known as the Fountain Formation. These rocks are sedimentary—that is, rocks that have been formed by broken fragments of older rock. The Fountain Formation was deposited approximately 280 million years ago, during a time geologists refer to as the Pennsylvanian Period.
Hope this helps!