A rock in the Snowy Range

Last month I found myself in Laramie, Wyoming, looking for birds, and
several friends and I took a short trip to the summit of the nearby
Snowy Range. And so I discovered some spectacular geology as interesting
as the pine grosbeaks and western pirangas. The Snowy Range (at least
what I saw of it) is mostly quartzite and greenschist, the product of
continental-scale metamorphism occasioned by some ancient orogeny.

And here and there I saw a few big chunks of metaconglomerate. The rock
consisted of white quartz pebbles, an inch or so in averaqe diameter,
somewhat flattened, in a darker ground. The pebbles had fuzzy edges, and
if the recrystalization had proceeded very much further all I would have
seen would have been a purplish gray quartzite.

So I got to thinking. How would a young-earth creationist explain this rock?

I know how I would. First we need a source rock for the pebbles. For
such big lumps of quartz that would be a coarse-grained granite. It
would form as a pluton intruded miles under the earth, taking millions
of years to cool so that the minerals would have time to grow such big
crystals. Then erosion and uplift would have had to bring the granite to
the surface, where the pebbles would be eroded out of it, and
transported by water toward the sea, in the process giving them their
rounded form. And then the pebbles would be deposited together with sand
in some high-energy process that didn't allow time for sorting of
particles by size -- perhaps an alluvial fan built by spring floods.
Eventually this fan would be buried deep enough that the mixed sand and
pebbles would be cemented together into a conglomerate. Later, that
continental-scale metamorphism I mentioned before would cause the
conglomerate to recrystallize, atoms migrating to form crystal bonds
between sand grain and sand grain, sand grain and pebble. Pressure on
the rock made plastic by heat would flatten the originally rounded
pebbles too. And so the sedimentary conglomerate becomes a much harder
metamorphic metaconglomerate. Finally, the buried metaconglomerate must
be uplifted, exposed by erosion, and eroded itself to produce the rock I
way.

So we have a multitude of steps, which I will briefly recap here:

1. Intrusion of magma.
2. Cooling to solid granite.
3. Uplift, erosion of overburden, exposure of granite.
4. Erosion and stream transport of granite pebbles.
5. Deposition of sediment.
6. Formation of conglomerate.
7. Metamorphism of conglomerate.
8. Uplift, erosion of overburden, exposure of metaconglomerate.
9. Erosion of metaconglomerate.

All within a year, or what? Can any YEC enlighten me as to the
geological facts?

.

Relevant Pages

  • Re: A rock in the Snowy Range
    ... consisted of white quartz pebbles, an inch or so in averaqe diameter, ... Then erosion and uplift would have had to bring the granite to ... pebbles would be cemented together into a conglomerate. ... between sand grain and sand grain, ...
    (talk.origins)
  • PotM nomination. Was: Re: A rock in the Snowy Range
    ... consisted of white quartz pebbles, an inch or so in averaqe diameter, ... Then erosion and uplift would have had to bring the granite to ... pebbles would be cemented together into a conglomerate. ... between sand grain and sand grain, ...
    (talk.origins)
  • Re: A rock in the Snowy Range
    ... consisted of white quartz pebbles, an inch or so in averaqe diameter, ... such big lumps of quartz that would be a coarse-grained granite. ... Then erosion and uplift would have had to bring the granite to ... pebbles would be cemented together into a conglomerate. ...
    (talk.origins)