Re(4): All kinds of odd observat...(from S. Kurth)

[N.MacLeod@xxxxxxxxx (N. MacLeod)]

-> In collecting for pollen I,ve seen that burrowed boundry between the
-> maestricht ian and the Hornerstown. Never thought of it as a good
-> boundary for k/t studies in N.J. because the top of the Cretaceous is
-> an erosion interval. So what am I overlooking?
->           Gil Brenner

The boundary between the Navesink and the Hornerstown is not necessarily
an unconformity.  Studies of formanifera by Olsson and Wise (1987)
indicate that the basal Hornerstown represents a condensed section
which spans the K/T boundary.  Gallagher (1993) also states
"In sum, micropaleontological evidence places the K/T boundary
within the lower part of the Hornerstown Formations, with no long-term,
major break in deposition and no evidence for an angular unconformity."

Articulated crocodile and turtle specimens are not uncommon in
this interval, and fragile complete ammonite steinkerns have also been
found, making it appear unlikely that this layer is reworked.
As for the burrowed zone below the Hornerstown, there are outcrops much
further north of Sewell, the best known site, that show no sign of being
burrowed.  Yet the same Maestrictian fauna is present.

Steve Kurth


Literature cited:

Gallagher, W. B.  1993.  The Cretacous/Tertiary Mass Extinction Event in
the Northern Atlantic Coastal Plain.  The Mosasaur, 3:75-152.

Olsson, R. K., and Wise.  1987.  Upper Maestrichtian to Middle Eocene
stratigraphy of the New Jersey slope and coastal plain.  In: J. E. van
Hinte, S. W. Wise, et al. (eds), Initial reports of the Deep Sea
Drilling Project, Vol. XCII, PP. 1343-1365.

Olsson, R. K. 1989.  Depositional sequences in the Cretaceous post rift
sediments on the New Jersey Atlantic margin.  Marine Geology, 90:
113-118.


----------------------------------------------------------------------------
Norman MacLeod
Senior Scientific Officer
N.MacLeod@nhm.ac.uk (Internet)
N.MacLeod@uk.ac.nhm (Janet)

Address: Dept. of Palaeontology, The Natural History Museum,
         Cromwell Road, London, SW7 5BD

Office Phone: 071-938-9006
Dept. FAX:  071-938-9277
----------------------------------------------------------------------------