And I’m trying not to be the Mean Old Atheist. 
There is a Vapor Canopy hypothesis, but that too end up creating a lot of heat. To make any of the Flood Geology theories survivable would require additional divine intervention to remove heat, at which point you may as well give up of a physical theory of a worldwide flood and just let it all be miracles.
As a wise friend once told me, none of this speculation about a real Flood is necessary to Christianity. It’s OK to consider it as allegory.
I suspect it was a lot nicer than the disjointed stem fragments you could find locally.
Crinoid segments are dotted around the beach at West Bay, particularly. Ammonites more at Lyme - Belamnites amongst the pebbles at Charmouth. They have ichthyosaurs etc as well, of course, but you don’t find them on the average picnic.
I have one lump of rock I found in Shropshire, with crinoids and brachipods from the Ordovician. What a pretty world we live in!
I and others have also mentioned coccoliths and chalk deposits. This is what chalk looks like under a microscope:
Chalk deposits are made up of tiny dead microorganisms that had a calcium based outer shell. They slowly settle out of the water as they die and very slowly create chalk deposits. This is what chalk deposits look like:
Needless to say, this is not what we should see with a recent global flood nor a young Earth.
Pretty much the entirety of Denmark is on top of such a layer, in some places ~350 meters thick chalk, made of coccolithophores. There’s a couple of rather famous surface outcroppings of this layer that are also popular sites for fossil hunting. I was at “Møn’s Klint” back in 2014, and took this picture that shows the scale:
Also found this awesome fossil sea urchin embedded in flint:
There’s also the even more famous “Stevn’s Klint” that contains the clearly visible K-T boundary, though I haven’t been there myself (yet).
That’s another problem for Flood geology. Why should there be an iridium-rich clay worldwide during the Flood (or after it)? It can’t be an asteroid impact, because that would have set the Ark on fire.
Fun. My 1-year-old was throwing sidewalk chalk into the dog’s water bowl the other day, and I realized he was noticing the water bubble up. I realized he was doing his own experiments. I myself wondered why it does that. Then he threw the wet chalk on the ground to see how it would break. These science conversations made me realize as a mom that what looks sort of destructive is kids learning. So as a mom, just like I read lots of books to them I better let them do lots of science even if it is messy!
I’m in the middle of two many things to research a reply right now, I apologize.
Very simple. Iridium runs faster than dinosaurs, but slower than most mammals.
Just to confuse you further, sidewalk chalk isn’t actually chalk; it’s gypsum.
Not if gopher wood is akin to asbestos.
This crazy idea of Catastrophic Pate Tectonics - have the propnents ever looked into the energy budget of such events? How much energy does it take to move the tectonic plates around (creating oceans and mountain chains, not once but multiple times), where is this energy coming from and where does it go? What about the heat generated by volumes of lava equal to entire oceans cooling and solidifying in a matter of years or months? What about the frictional heat of the rock deformations? What does all that heat do to the ocean waters (and the poor people floating on them in a wooden boat)?
Much of mountain building consists of plastic deformation of rocks (folding and metamorphosis) that is the accumulation of myriads of tiny dislocations in the crystal lattices of the minerals involved - at the rates required for CPT rock would cease to be rock. Rock will melt long before such deformation rates could be achieved.
Would an entirely different magnetic field for earth fix or change any of these problems?
No, changing the magnetic field of Earth would not change how much heat is released by friction when rocks deform, or when rock surfaces slide against each other.
No. But of course we do know what has happened to the earth’s magnetic field over time. A great many reversals of direction are recorded in the rock record. There is no effect on plate tectonics, radioactive decay, life, or TV reception.
Not really at all.
Have you ever touched a nail you have been hammering, or a screw you have just backed out, and been surprised at how hot it has become? That is just an exhibit of the conservation of mass and energy. Energy cannot just come out of nowhere, and it cannot just disappear. Now when geologists talk about tectonic drift, they are referencing plate movement of a few millimetres or centimetres per year. Even that small movement takes all the immense power of all the heat in the earth, generated by radioactivity and tidal friction. Heat generates movement, and friction generates heat.
Now YEC comes along and says that plates moved not just centimeters per year, but kilometers per hour or some such scale. This might seem like just more of the same, so why not, but it is really physically impossible, like jumping across the grand canyon is impossible even if you can jump across a brook. Firstly, there is nothing close to sufficient in terms of energies required to power such movement to begin with. But if there were, and such movement occurred, the heat would be colossal. The crust would melt, the waters of the flood would flash to steam. It would not be Noah’s flood, it would be Noah’s scalding steam bath. 
