The Floors of the Ocean: 1. The North Atlantic: Text to accompany the physiographic diagram of the North AtlanticHeezen, Bruce C.
Science
The Floors of the Ocean: 1. The North Atlantic: Text to accompany the physiographic diagram of the North Atlantic
Heezen, Bruce C.
Ocean bottom
In the Georges Bank area a series of prominent benches continues along
the continental slope. If these are structural benches we should be
able to trace them up the canyons and thus determine the dip of the
formations. If the benches are the result of step faulting or landslide
scars they would not extend up the canyons. In order to test these
alternatives, a series of profiles has been plotted from the surveys of
the Coast and Geodetic Survey. A line was drawn which paralleled most
of the contours of the continental slope for 20 miles or more (Fig.
20). A second line was drawn at right angles to this first strike line.
All sounding lines in the area were projected to this second dip line
along lines parallel to the strike line, and plotted as a composite
projected profile (Fig. 21). If the first line was essentially the
strike of rock layers then we should be able to determine the dip of
the beds by picking the successive benches as they occur on successive
profiles across the canyon. In Figure 21 the results of the analysis
of Oceanographer and Hydrographer canyons are presented. The dredge
hauls by Stetson (1949) have also been projected on this profile. We
see that a major bench occurs at _A_ which passes below the hauls
in which fossiliferous Navarro (Upper Cretaceous) was obtained and
through the upper limit of the hauls where Matawan (Upper Cretaceous)
was obtained. Thus if this horizon or one closely parallel to it is
the Navarro-Matawan contract, the apparent discrepancies of the depth
ranges of Stetson's dredge hauls are explained. Much more important to
the present study is the dating of a prominent structural bench.
[Illustration: FIGURE 21.--_Two projected profiles of Georges Bank
canyons_
Location of soundings for profile (a) shown in Figure 20. Soundings
projected along strike to construct profile. Soundings for both
profiles taken from Coast and Geodetic Survey Chart 1313.]
[Illustration: FIGURE 22.--_Geologic section at Cape Hatteras, Virginia_
Well logs from Swain (1947) and Spangler (1950). Four sounding profiles
made by R. V. ATLANTIS are projected to profile. Note that resistant
formations form prominent structural benches on continental slope.]
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account