Anyone who knows me well, knows that Science and Vera are a bit of a joke when used in the same sentence. Needless to say, I did not have answers.
I did, however, have access to the Internet, and so we emailed our questions to "Ask a Geologist", a free, online service provided by the US Geological survey.
Here's what we got within a few short days from a friendly geologist:
Q - Regarding sedimentary rocks: We read that they are formed by by heavier layers pushing down on top of layers of tiny sand and rock particles underneath, for example, under the water, in the ocean. We want to know why don't the tiny pieces at the bottom just move out from under the heavier ones on top? How do they just stay in place so they can be compacted? We don't understand.
A - A small grain at the bottom of a pile can not move out of the way because its neighbors keep it from escaping. The grain along with its neighbors are blanketed, trapped, and squished.
Q - Were all sedimentary rocks once igneous?
A - The ultimate, original source of all the material in sedimentary rocks is igneous rock. But, that material may have gone through many transformations on the journey from igneous to sedimentary. Some sedimentary rock is made from the hard parts of sea critters (think corals & sea shells), the critters formed their shells using calcium dissolved in the water around them, the calcium that is in ocean water comes from the weathering of minerals in igneous rocks.
Q - How does intense pressure make something really hard? (ie. metamorphic rock)
A - Pressure makes metamorphic rocks hard similar to the processes involved as a child compresses loose snow into a snowball. some of the spaces between grains are 'squeezed' out and some of the crystals change shape to fit the spaces.
Thank you, Gregg E. Hileman from the U.S. Geological Survey!