Re: Precambrian geology (1)

Jonathan Clarke (
Wed, 14 Apr 1999 18:00:23 +1000

Hi Allen

Allen Roy wrote:

> > What criteria do you use to decide when the biostratigraphic succession
> of one
> > area is no longer applicable?
> I have mostly been reporting what I have read. I have not looked into it
> myself.

Don't you think you should if you are going to criticise both biostratigraphy
and those who use it?

> This idea is new in Creationary circles. It is being tossed about that the
> strata that has been fairly recently reinterpreted as turbidite might
> instead be interpreted as mega-tsunami deposits. Modern tsunami deposition
> is very similar to turbidite deposition. If a global catastrophe occurres
> because of a series or family of asteroids striking the planet in a short
> time, one might ask are there any non-impact related deposits.

Impact crating and its environmental effect is not a new idea or restricted to
flood geological circles. There is an extensive literature on impact cratering
and its effects. A quick search on georef using words such as "asteroid
impacts", astroblemes, etc., turned up over a thousand references. Essential
reading would include compilations such as Silver & Schultz (1982), Sharpton &
Ward (1990), Hodge (1994), and Rhyder 1996. Detailed references at the end
of the message. These consider the effects on impacts from small local events
up to ones that cause global catastrophe. Nobody should talk about impact
effects without considering this literature.

God Bless



Rhyder, G. et. al. 1996 (eds). The Cretaceous-Tertiary event and other
catastrophes in earth history. Geological Society of America Special paper

Sharpton, V. L. Ward, P. D.(eds). 1990. Global catastrophes in earth history :
an interdisciplinary conference on impacts, volcanism, and mass mortality,
Boulder, Colo. Geological Society of America special paper 247.

Silver, L. T.Schultz P. H. (eds) (1982). Geological implications of impacts of
large asteroids and comets on the earth. Conference on Large Body Impacts and
Terrestrial Evolution: Geological, Climatological, and Biological Implications
(1981 : Snowbird, Utah. Geological Society of America special paper 190.