Here's another possiblility:
5. Diatoms lived in upland waters preflood, and were not washed into the
sediments until rising water eroded those uplands (so they are not found in
Paleozoic deposits). During the high-water phase of the Flood, when
had mixed into the ocean, some species found conditions favorable for
massive multiplication, generating the multitudes of diatoms (with their
C26 steranes) found in Cretaceous deposits. Then, when the floodwaters
receded, leaving giant lakes in many places around the world, some of the
lakes provided appropriate nutrients, temperatures, etc. for extremely
prodigious diatom multiplication (different species in different areas),
until the nutrients etc. were exhausted or the lake was filled, leaving the
mid-upper Tertiary diatomite deposits we mine today.
>The global flood model holds that the pre-flood biosphere contained almost
>all the plants and animals which are alive today. This means that evidence
>of the plants and animals should be found in the fossil record. Diatoms are
>microscopic plants that should have lived in the preflood oceans, yet they
>first appear in very small numbers in the Triassic rocks. According to the
>flood model, they were in existence in the waters of the flood prior to
>this time. Diatoms become abundant in the Cretaceous and later rocks. But
>there is no fossil evidence of their pre-flood or early existence. And
>what is surprising is that diatoms produce unique chemicals which are
>modified and then found in oils around the world. These chemicals first
>appear in oils which come from Cretaceous rocks, which is coincident with
>the fossil occurrence of abundant diatoms. September Geology published a
>study of the biological chemicals left by diatoms in petroleum.
>"Biomarkers, molecular fossils, are organic compounds in Holocene to
>Precambrian sedimentary deposits that can be related to specific chemical
>compounds produced in the biosphere. We demonstrate here that
>24-norcholestane biomarkers, i.e, C26 steranes (saturated hydrocarbons
>having a steroid skeleton), can be useful to constrain the age and
>paleolatitude of geologic samples. The biological precursors of
>24-norchloestanes remain unclear, but samples from more than 100 basins
>provide evidence that 24-norcholestanes show an initial increase above
>background in Jurassic oils, but they increase dramatically in Cretaceous
>oils, coincident with diatom evolution. The highest ratios are found in
>oils and rock extracts from Oligocene or younger marine siliceous source
>rocks in which the sources were deposited at paleolatitudes greater than
>30[deg] N" ~ A. G. Holba et al, "24-norcholestanes as Age-sensitive
>Molecular Fossils," Geology 26(1998):783-786, p. 783
>Now, what are the possibilities:
>1. Diatoms lived in the oceans prior to the Cretaceous part of the flood,
>but they didn't die. Given the supposed violence of the flood, this seems
>unlikely as the waters should have been thoroughly mixed up and the
>microscopic diatoms should have been found with microscopic conodonts and
>other small evidences of life in the Paleozoic
>2. Diatoms fled with the dinosaurs and were washed into the sea later.
>This is Morris' hydrodynamic sorting and ecological zonation hypothesis.
>Morris suggests that dinos and men were able to flee to the hills and avoid
>burial in the early part of the flood and escape early burial. It seems
>difficult to envision diatoms fleeing to the hills.
>3. Diatoms only lived in freshwater before the flood and they didn't enter
>the flood until the waters washed them into the sea. The difficulty with
>this is that fresh water deposits, without any diatoms are found in the
>4. Diatoms actually evolved in the Cretaceous rocks as evolution and
>The same line of reasoning goes for another chemical found in petroleum,
>oleananes, which are manufactured only by angiosperms. Angiosperms first
>appear early in the Cretaceous but don't become numerous until the
>Maastrichtian at the very end of the Cretaceous. And guess what?
>Oleananes also follow this pattern.
> "The results of the oleanane analyses are broadly comparable with
>those found for fossil angiosperm occurrences. The relative concentrations
>of oleanane to hopane, excluding the unusual Middle Jurassic and Neocomian
>occurrences, begin low, near the detectable limit of 3% during the Early
>Cretaceous and steadily incrase to a plateau during the latest Cretaceous.
>Then, during the Tertiary there is a major increase." J. Michael Moldowan
>et al, "the Molecular Fossil Record of Oleanane and Its Relation to
>Angiosperms," Science 265(1994):768-771, p. 769
>The question for the global flood advocates is: Why do the chemicals found
>in petroleum not show the presence of preflood diatoms and angiosperms?