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UNITED STATES COASV G U AUR D

OCEANOGRAPHIC
REPORT No. 22

Woods Hole OceBnographic Institution
ATLAS - GAZtTTEER COLLECTION

CG 373-22

PHOTOGRAPHIC INVESTIGATION OF SEDIMENT
TEXTURE, BOTTOM CURRENT ACTIVITY, AND
BENTHONIC ORGANISMS IN THE
WILMINGTON SUBMARINE CANYON

U.S.C.G.C. ROCKAWAY- SMITHSONIAN INSTITUTION
CRUISE (RoS2)

December 1967

PLEASE RETURN

TO

li^TITUT!ON DATA LIBRARY

McLean

UNITED STATES COAST GUARD

OCEANOGRAPHIC

UNITED STATES COAST GUARD OCEANOGRAPHIC UNIT

REPORT No. 22

CG 373-22

PHOTOGRAPHIC INVESTIGATION OF SEDIMENT
TEXTURE, BOTTOM CURRENT ACTIVITY, AND
BENTHONIC ORGANISMS IN THE
WILMINGTON SUBMARINE CANYON

U.S.C.G.C. ROCK AWAY- SMITHSONIAN INSTITUTION
CRUISE (RoS2)

December 1967

Daniel /. Stanley

Division of Sedimentology, Smithsonian Institution,

Washington, D.C. 20560

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Gilbert Kelling

Department of Geology, University of Wales
at Swansea, Great Britain

WASHINGTON, D.C. $ FEBRUARY 1968

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Abstract

This report describes the investigation of the sea floor in the vicinity,
of Wilmington submarine canyon (38°00'N to 38°35'N Lat. ; 72°35'W to
73°40'W Long.) by means of underwater photography. The techniques
of both equipment operation and of interpretation are detailed. More
than 1200 photographs were obtained from a net of 54 stations on
the continental shelf, slope and upper continental rise in the region
encompassing the Wilmington submarine canyon. These photographs,
linked to precise navigation, enable assessment of the areal distribution of
several sedimentary attributes, notably the texture of bottom sediments,
the patterns of recent current activity (neocurrents) and movement of
materials, and the role of benthic organisms in modifying bottom sediments.

Studies of bottom texture indicate that the head of this canyon is
presently acting as a sediment trap. Admixtures of sand, silt and evten
coarse gravel are characteristic of the headward part of the canyon,
whereas silt (near the canyon) and silty clay are dominant on the lower
slope and upper rise. However, patches of gravel, sand and silt are
associated with rock-ledges on the lower part of the Nyckel Ridge, a
topographic elevation forming the southern margin of Wilmington Canyon.

The inferred patterns of recent bottom current movement suggest
westward supply of course shelf sediment to the canyon head, some
southerly, down-axis transport in the shallower portions of the canyon, and
weaker southwesterly moving contour currents on the outer part of the
upper rise. Significant transport of coarse sediment in a general northerly
direction has also been observed in the vicinity of the Nyckel Ridge, near
the base of the continental slope.

Organisms living on or near the sea floor profoundly affect bottom
sediment, thus the distribution of the more important groups of such
animals has been plotted.

Although underwater photography has proved valuable in elucidating
the nature of the bottom in this canyon, some caution must be exercised
in extending these conclusions to the geologically recent past. Cores
indicate that the thin, fine-grained sediment veneer presently being
reworked by benthic organisms actually masks the effects of recently active
sedimentation in the canyon area. The combined pattern of current activity
and sediment distribution as observed in the bottom photographs suggests
that the Wilmington submarine canyon has played an important role in
funnelling sediments from the shelf area to the deep-sea in the recent past.

CONTENTS

Page

Abstract U1

I. Introduction 1

II. Area of Study 3

III. Procedures 7

IV. Results .. 81

General 81

Sediment Texture _ . 81

Inferred Bottom Current (Neocurrents)

and Sediment Movement . 81

Benthic Organisms 87

V. Discussion 88

VI. Acknowledgements 91

VII. References .___..... 92

ILLUSTRATIONS

Frontispiece: USCGC ROCKAWAY (WAGO 377)

Figure

1. General bathymetry of the Wilmington submarine canyon area — 2

2. Track of the USCGC ROCKAWAY (WAGO 377) during cruise RoS„

4-10 December 1967 5

3. Direction and distance of drift on photographic stations and location

of free-fall cores - 6

4. Photographs of camera-rig used on cruise RoSL. 8

5. Typical "pinger-traces" of camera-rig during descent, bottom photog-
raphy near the sea-bed, and ascent as indicated on PESR record 9

6. Diagram illustrating the relative dimensions of the main components

of the camera-rig used on cruise RoS2 10

7. Chart illustrating the distribution of the texture of surface sediment

as determined from bottom photographs of the Wilmington sub-
marine canyon area 82

8. Patterns of recent current movement in the region of Wilmington

submarine canyon 83

9. Distribution of major groups of organisms affecting bottom sediment

on the shelf and slope of the Wilmington submarine canyon area . 84

10. Distribution of major groups of organisms affecting bottom sediment
on the shelf and bathyal regions in the vicinity of Wilmington
submarine canyon 85

Photoplate 1-34. Bottom photographs obtained in the Wilmington sub-
marine canyon area during RoS2.

TABLES

Page
I. Station positions and depths on USCGC ROCKAW AY-SMITH-
SONIAN Cruise (RoS2) 93

II. Summary of data from photographic investigation in the Wilmington

Submarine canyon area (Cruise RoS2) 94-95

I. INTRODUCTION

Submarine canyons are large, steep-sided,
generally sinuous depressions incised into the
continental slope and rise and often heading on
the shelf. They occur on the margins of most
continental regions and their mode of origin
has long been a source of debate and contro-
versy among geologists and others concerned
with the morphology of the sea floor (Lawson,
1893; Pruvot, 1894; Daly, 1936; Johnson, 1938;
Kuenen, 1950; Shepard, 1963; and others).
More recently it has been suggested that sub-
marine canyons are responsible for funnelling
sediment from shallow shelf regions, down the
continental slope and onto the deep ocean floor
of the rise and abyssal plain beyond (Shepard,
1965a). Submarine canyons best studied to
date are of the type that head on relatively
narrow shelves in tectonically active areas
(Shepard and Dill, 1966). Canyons located off
wide shelves in structurally stable areas have
received less attention.

A program of investigation undertaken by
staff of the Division of Sedimentology, U.S.
National Museum, Smithsonian Institution,
with active cooperation and support of the U.S.
Coast Guard Oceanographic Unit, has as long-
term objective, the detailing of the geometry
and sedimentary processes associated with can-
yons in general. One of the major purposes of
this study is the formulation of a sedimentary
model for modern canyons located on shelves
off low coastal regions which are apparently
tectonically stable. Four submarine canyons
(from North to South: Wilmington, Baltimore,
Washington and Norfolk) located on the At-
lantic seaboard of the United States southeast
of Delaware and Chesapeake Bays are of parti-
cular interest in this respect (see inset, Fig. 1).
All four of these canyons, mapped in consider-

able detail by Veatch and Smith (1939), are
deeply incised as much as 12 nautical miles
into the outer edge of the wide continental
shelf. The canyons form two distinct paired
systems (Wilmington-Baltimore and Washing-
ton-Norfolk), each consisting of a long and a
closely associated shorter canyon, as noted by
Pratt (1967). The selection of these specific
canyons for study was, in part, determined by
logistics, i.e., their proximity to major ports
which facilitates repetitive runs over the same
area and ease of monitoring with different ma-
rine geological and oceanographic techniques.

The cruise described in the following ac-
count was made by the USCGC ROCKAWAY
(WAGO 377) during the period 4 to 10 Decem-
ber, 1967 and is referred to as cruise RoS:.
The purpose of this cruise was to obtain photo-
graphic records of the ocean floor in the vicin-
ity of Wilmington submarine canyon, the most
northerly of the 4 features. Free-fall cores of
the bottom sediment were also collected at sev-
eral of the photographic stations. This, the sec-
ond of a series of 5 cruises in this area, was
preceded by a morphological-subbottom inves-
tigation (RoS,, Kelling and Stanley, in prepa-
ration) and followed by bottom sampling
(RoS,) and underwater television (RoS,)
programs (data presently under examination
at the Division of Sedimentology, Smithsonian
Institution and Department of Geology, Uni-
versity of Wales at Swansea). This report pre-
sents photographic data obtained during RoSj
and a summary of results.1

1 A published presentation made by the authors at
the Ocean Sciences and Engineering of the Atlantic
Shelf Symposium, Marine Technology Society, Phila-
delphia (Stanley and Kelling, 1968b) is an interpre-
tative summary of the data presented in this Report.

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II. AREA OF STUDY

Wilmington Canyon originates near the edge
of the continental shelf approximately 95 nau-
tical miles east-southeast of the mouth of Dela-
ware Bay. The canyon head may be traced
northeastward (landward) to a minimum depth
of 45 fathoms, at which point it is incised into
the shelf for a distance of about 10 miles (Fig.
1). From this point the canyon trends south-
southwest for nearly 7 miles to an axial depth
of 380 fms and then makes a sharp turn to a
general southeasterly course. This course is
maintained to an axial depth of about 1000 fms,
near the base of the continental slope, and is in-
terrupted only by an abrupt turn to the east for
almost 3 miles at 700 to 780 fms. The canyon
trends almost due east across the upper part of
the continental rise where it gradually dimin-
ishes in relief. Beyond the 1300 fms isobath
the canyon, which would better be described as
a submarine valley because of its low relief, ex-
tends toward the east-southeast to a depth of
about 1800 fms. The gradient of the canyon
axis become steeper and the relief increases in
the lower rise (1800-2500 fms). The canyon
trend is almost due south between 1800 and
2000 fms, then becomes generally southeast.

The gradient of the canyon axis is main-
tained at between 1 in 20 and 1 in 25 through-
out most of the headward portion and on the
upper continental slope. However steeper gra-
dients are encountered locally, in the vicinity
of the acute changes in the trend of the canyon
axis described above. Beyond an axial depth of
800 fms the gradient decreases first to 1 in 50
then, at about 1350 fms, to about 1 in 90.

Followed from its head towards the regional
shelf-break the canyon gradually increases in
dimensions, attaining both its maximum width
(6 miles) and its greatest relief (approxi-
mately 500 fms) at the regional shelf edge. In
this headward portion, the canyon is generally
steep-sided with lateral slopes of 10° to 20°
which frequently expose bedrock. The trans-
verse profile of the canyon tends to be acute
and V-shaped in the shallower part of the head

but becomes less acute or even flat-based be-
yond about 400 fms. The walls of the canyon in
this headward region are extensively modified
by many depressions and secondary ridges, in-
cluding several cirque-like tributary canyons
as much as a mile wide (Fig. 1).

Descending the continental slope the canyon
diminishes both in width and depth. Near the
1000 fms isobath the canyon is a sharply in-
cised feature 0.6 n. miles wide and with a relief
of some 45 fms. At an axial depth of 1350 fms
the width of the canyon has diminished to 0.3
n.miles and the V-shaped depression is barely
30 fms deep. At greater depths the Wilmington
submarine valley is an inconspicuous, rather
broadly terraced depression which includes one
or more narrow, gully-like features, usually
less than 0.2 n.m. across and 10 to 20 fms deep.
An important morphological high (here
termed the Xyckel Ridge, after Veatch and
Smith, 1939) runs parallel to Wilmington Can-
yon from the shelf, down the continental slope
and across the rise to the 1400 fms isobath. It
is described in detail elsewhere (Stanley and
Kelling, 1968a, 1968b). Other subsidiary can-
yons and ridges, most of them originating on
the middle or lower regions of the slope, occur
both to north and south of the main Wilming-
ton Canyon.

In contrast to the numerous secondary de-
pressions which mark the course of this fea-
ture in its headward region and across the con-
tinental slope, only one tributary canyon can
be linked to the Wilmington submarine canyon
as it crosses the upper continental rise. This
tributary originates on the north side of the
Nyckel Ridge near the 1200 fms isobath and
eventually merges into the Wilmington sub-
marine valley system at about 1500 fms (Fig.
1).

A further feature of morphological interest
in this area is the marked contrast in bottom
relief between the upper and lower portions of
the continental slope. Except in the immediate
vicinity of the major canyons, the shelf-break

and upper part of the slope are relatively
smooth, with only minor undulations in both
slope-parallel and slope-normal directions.
However, below the 500 fms isobath the bot-
tom morphology becomes appreciably rougher,
the slope being modified by many ridges and
hollows with a slope-normal relief often ex-
ceeding 150 fms. This rugged topography ex-
tends on to the uppermost part of the continen-
tal rise but beyond the 1200 fms isobath the re-
lief is less conspicuous. Here a few large, iso-
lated ridges are separated by wide, relatively
smooth depressions (Fig. 1).

The ship's track for cruise RoS, (Fig. 2)
follows a broadly rectilinear pattern compris-

ing legs which are alternately parallel and per-
pendicular to the course of the canyon axis.
Such a track (total of 502 n.miles) not only
provides extremely useful bathymetric data
from PESR records but also facilitates the
creation of a net of bottom camera stations
which encompasses not only the canyon itself
but also the adjacent areas of the shelf, slope
and rise (Fig. 3, Table 1). Slope corrections
were applied to soundings after the method of
Shalowitz (1930). Soundings from Coast and
Geodetic Survey Charts H5350, H6200 and
H5713 were utilized to amplify the bathyme-
tric data in a few areas of the shelf and upper
slope.

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III. PROCEDURES

The camera rig used on this cruise was on
loan from the U.S. Naval Oceanographic Office,
Washington, D.C. and the operation of the
camera was supervised by personnel from that
office, Messrs. Robert K. Oser and Martin G.
Fagot. The photographic system consists of an
E.G.&G. Model 204 Underwater Camera used
in conjunction with a Model 214 Stroboscopic
Light source. These are mounted in a steel
frame which also carried an E.G.&G. Pinger
System (Fig. 4). An E.G.&G. Model 260 Cur-
rent Compass was suspended on a nylon cord
below the frame. The camera system was low-
ered and raised off the stern-mounted A-
frame with 3/16" wire using a steam winch.

The operation of such a photographic system
has been described in detail by Edgerton
(1967) and Hersey (1967). It is sufficient to
note here that the camera is a 35 mm self-cy-
cling, automatic unit, synchronized with the
light-source to permit one exposure every
18-23 seconds. At shallow stations the camera
and light source were activated on deck and
many frames, therefore, consist of shots of the
water column taken during lowering and rais-
ing of the rig. At deeper stations, a timing de-
vice was used to activate the camera and light
source after a preset interval corresponding to
the estimated time required to lower the rig to
the bottom.

The camera and light source were mounted
in a vertical position (Fig. 4) in order to ob-
tain more accurate observations of the orienta-
tion of bottom features with respect to the
compass. This resulted in some consequent loss
of bottom relief as compared with oblique
mounting. Black and white TriX-Pan film was
used for most stations but one 100 ft roll of
color film (Ektachrome ER, Type B) was used
at Stations 40-43 inclusive (See Table II).

The use of a pinger allows the course of the
rig to be followed on the PESR record during
lowering and raising and also while the cam-
era is actually photographing the sea-bed (Fig.
5) .. The use of a supplementary oscilloscope

also enabled more precise control of the cam-
era's position at between 0.5-2 fathoms above
the bottom. Subsequent evaluation of the pho-
tographs indicated that in order to ascertain
details of the bottom texture, structures and
organisms the optimum height for the camera
is between 0.5 and 1 fms above the seabed.

In addition to its function as an orientation-
datum, the suspended compass furnishes a use-
ful means of estimating the size of objects on
the bottom. This is achieved by determining the
diameter of the shadow of the compass or the
vane by a comparison with the measured dia-
meter of the compass itself (3 inches) or the
length of the vane (10 inches) knowing the spa-
tial relationship of the compass with respect to
the light source and the camera lens (Fig. 6).

Throughout the cruise navigational fixes ac-
curate to within ± 0.25 miles were obtained
by LORAN C. Fixes were taken at 6-minute in-
tervals while changing stations and further
fixes were obtained during the lowering and
raising operations. The total time spent at a
single camera station comprises components
due to lowering and raising the camera-rig in
addition to the time actually spent in photo-
graphing the sea-bed (usually 10 to 15 minutes
on the bottom). The total period of time may
amount to more than an hour for deep stations
and during this interval the ship (and the
trailing gear) will drift for a distance and in a
direction which is dependent on conditions of
sea, wind, etc. On this cruise the total drift on
station varied between 0.2 and 2.1 nautical
miles (see Table I). The distance and direction
of drift during the period when the camera
was close to the bottom are indicated in Fig. 3

Prints from each of the ten 100 ft reels of
film used on this cruise were enlarged to a size
of 3i->" x 2" on continuous strip which was
threaded on to a pair of rollers for examina-
tion. Each photographic frame is accompanied
by a data-chamber which includes the film roll-
number (numbered from 1 to 10), the consecu-

Figure 4. (a): Photograph of sled-mounted camera rig used on cruise RoS2.
1 — Camera ;
2 — Pinger transducer;
3 — Stroboscopic light-source.

(6): Photograph of camera-rig being lowered over the stern of the USCGC
ROCKAWAY (WAGO 377) December 7, 1967.

1 — Camera ;

2 — Battery packs for light and camera.

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Figure 5. Typical "pinger-traces" of camera-rig dur-
ing descent, bottom photography near the sea-bed,
and ascent as indicated on PESR record.

(a) Camera Station 23, near shelf-break, north of

canyon head.

(b) Camera Station 28, near shelf-break on open

slope, southwest of canyon.

P — trace given by pinger attached to
camera-rig;

B — true bottom (sediment-water inter-
face) ;

M — multiple of bottom and pinger-trace.

tive frame-number and a clock. This allows the
position of each frame to be accurately located
with respect to the known position of the ship
at a given instant of time. Moreover, each

frame may be linked to timed events on the
PESR record, allowing more precise location
as to depth of individual frames and groups of
frames within each station.

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COMPASS AND VANE

Figure 6. Diagram illustrating the relative dimensions of the main
components of the camera-rig used on cruise RoS:.

10

Each print was carefully examined by means
of an illuminated table magnifier and the re-
sults of this examination recorded on a stan-
dardized form. In addition to statistics con-
cerned with the operation of the camera, the
station number and location, this form details
the sedimentary and organic features observed
within the photographs.1 These include the in-
ferred texture of the bottom sediment ; the na-
ture, orientation and dimension of ripple-
marks and other features indicating current
movement, including oriented organic struc-
tures; the occurrence and relative abundance
of shell, and the presence of living organisms
and their traces.

1 Copies of the completed forms used in this study
have been lodged with the National Oceanographic
Data Center, Washington, D.C. The original negatives
and prints are housed in the collection, Division of
Sedimentology, U.S. National Museum, Washington,
D.C. 20560.

The dimensions of objects and structures in
the photographs can generally be determined
by comparison with the compass shadow as de-
scribed earlier or by relation to other objects
of known approximate diameter in the photo-
graph, such as sand-dollars, etc. The texture of
the sediment forming the bottom may be indi-
cated directly (as in the case of gravel or
coarse sand) or it may be inferred from asso-
ciated features, such as ripple marks. For ex-
ample, the firmness of the bottom and the pro-
portion of mud (clay and silt) in the sediment
is indicated by the character of the mark made
on the bottom or the nature of the cloud of sed-
iment raised by the compass or vane striking
the sea-bed. The size and character of sedimen-
tary structures and of organic tracks, burrows
and mounds provide further evidence of the
nature of bottom sediment type.

11

PLATE 1
Fig. A. — Station 1, outer shelf, north of canyon head, 46-50 fms.
Figs. B-D. — Station 3, outer shelf, northwest of canyon head, 35-37 fms.
Figs. E-F. — Station 6, canyon head, northwest wall, 115-120 fms.

A, Coarse shelly sand; faint, slightly sinuous symmetrical ripple marks with crest
orientation of 015 -19.1 "; abundant disarticulated pelecypod shells; 2 canceroid
crabs (arrows) and 1 fish (Urophycis) resting on bottom.

B, Shelly, silty sand; straight short-crested asymmetric ripple marks (old); current
toward WSW; large articulated pelecypod shells, partially buried. Concave-up
attitude of the shells suggest weak bottom current activity.

C&D, Bottom similar to B; ripple crests are sharper, with suggestion of current
interference pattern. Note turbid state of water in D.

E, Sandy, somewhat shelly, silt; poor ripple mark development; ripple crest
orientation 145°-325°; disarticulated, partially buried pelecypod; small fish near
compass vane.

F, Bottom similar to E. Compass striking bottom reveals muddy nature of bottom.

12

PLATE 1

13

PLATE 2
Figs. A-B. — Station 6, canyon head, northwest wall, 115-120 fms.
Figs. C-F. — Station 7, outer shelf, east of canyon head, 58-82 fms.

A, Sandy, somewhat shelly, silt; interference ripple marks with a dominant crest
orientation (solid line) of 120°-300° and small ripple crest orientation (dotted
line) of 030°-210°; cloud trailing compass reveals muddy nature of bottom;
hagfish (Myxine glutinosa) resting on bottom.

B, Bottom similar to A; fish (Urophycis) resting on bottom (arrow).

C, Shelly, silty sand; straight asymmetric, anastomosing ripple marks indicating
current movement towards west. Shell in ripple troughs.

D-F, Bottom similar to C; ripple marks more linguoid in form. Note fish (in E
and F) and canceroid crab (arrow, in F).

14

PLATE 2

15

PLATE 3

Figs. A-F. — Station 8, canyon head, east wall, 110-128 fms.

A, Sandy silt; interference ripple marks with dominant crest orientation of
155°-335° (old ripples); partially buried shell.

B, Bottom similar to A; flat fish (arrow 1) and depression (arrow 2), possibly
formed by fish. The steep margin of depression indicates cohesiveness of the
bottom sediment.

C, Bottom similar to above; skate and two other fish; canceroid crab in center of
photo.

D, Close-up of bottom showing cell-like, interference ripple pattern, also possible
"fish-nest" depression (arrow) and small tracks made by crabs.

E&F, Bottom similar to the above, with cloud of mud trailing compass. Note
canceroid crab and partially obscured flat fish (arrow) in E, and fish in F.

16

PLATE 3

17

PLATE 4
Figs. A-D. — Station 9, canyon head near axis, 195-208 fins.
Figs. E-F. — Station 10, outer shelf, west of canyon head, 57-59 fms.

A&B, Silty hottom with poorly defined (old) ripple marks. Burrows in lower left
corner of A and upper part of B; possible crustacean tracks on left margin of B.
C&D, Bottom similar to above. Tubes of polychaete worms (arrows), and hagfish
(Myxine) (in D).

E&F, Coarse shelly sand; straight asymmetric ripple marks with rounded crests
indicating current toward the west. Concentration of shell in ripple troughs and
partially buried larger shells in F; Concave-up attitude of shells suggest only
weak bottom current activity.

18

PLATE 4

19

PLATE 5
Figs. A-B. — Station 11, outer shelf, west of canyon head, 54-56 fms.
Fig. C. — Station 12, outer shelf, west of canyon head, 52-55 fms.

A&B, Shelly silty sand, with straight asymmetric ripples indicating current to-
ward WNW; canceroid crab (arrow in A) and starfish, common asteroid.
C, Sandy silt, with straight symmetrical ripple marks (crest orientation: 070°-
250°); some current interference indicated. Mud or silt partially covering ripples
produces a mottled effect.

20

PLATE 5

21

PLATE 6

Figs. A-F. — Station 13, canyon head near axis, 258-278 fins.

A-F, Poorly sorted, gravelly silty mud; large subangular cobbles covered by
coelenterates (sea-anemones?) and a veneer of mud. Particularly large boulder
(>60 cms. diameter) is designated by arrow in C. Cloudy appearance of all
photographs suggest presence of substantial amounts of suspended sediment.

22

PLATE 6

23

PLATE 7

Figs. A-F. — Station 14, canyon head, east wall, 100 fms.

A-C, Shelly, gravelly, sandy silt; slight northeast-southwest lineation of pelecypod
shells (mostly concave up and partially buried). Arrows in A, B, and C show
lobsters (Homarus americanus) adjacent to cobbles; fish resting on bottom, in C.

D-F, Bottom similar to above; hint of ripple interference in D and E; two fish in E;
unidentified organism or object in F (arrow).

24

PLATE 7

^

I

25

PLATE 8

Figs. A-P. — Station 15, outer shelf, east of canyon head, 65 fms.

A-D. Shelly, gravelly sand; straight, anastomosing asymmetric ripple marks

indicate current toward WNW. Shell hash concentrated in troughs; several

large, partially buried pelecypod valves, in A.
E-F, Bottom similar to above; ripple marks more linguoid in form but similar

orientation; fish (Urophycis) near bottom, in E.

26

PLATE 8

27

PLATE 9

Figs. A-F. — Station 16, outer shelf, east of canyon head, 125-135 fms.

A-F, Muddy silty bottom (cloud trailing compass in A indicates silty nature of
sediment; indication of straight asymmetric ripples with some interference, pre-
dominant current trend toward the WNW). Tube-dwelling polychaete worms
(Hyalinoecia) in all photographs (note particularly long tube in A, and tendency
towards parallel orientation in A and B) ; coelenterate in C, crab (Cancer-sp.)
in D, flat fish (arrow) in E, and probable "fish nest" depressions in F.

28

PLATE 9

29

PLATE 10
Fig. A. — Station 17, canyon head, near axis, 350 fms.
Figs. B-C. — Station 18, outer shelf, west of canyon head, 70-75 fms.
Figs. D-F. — Station 22, canyon head, near axis, 395-405 fms.

A, Muddy silt bottom with occasional small pebbles (arrows 1, 2) ; suggestion of
low amplitude ripple marks; crest orientation of 005°-185°, burrow, right of
compass vane.
B&C, Sandy silt, slightly shelly; patchy distribution of silt veneer produces mottled
effect. Depression (arrows) in upper right corner of B, caused by impact of
compass; reveals cohesive nature of sediment. Interference ripple marks (crest
orientations: 020°-200° and 165°-345; dominant current towards west), lumps
in lower left corner of B may be small pebbles or faecal casts; pelecypod shells
partially buried and concave up; fish near bottom in C.
D, Silty mud, granular nature of bottom probably due to faecal pellets. Two

asteroid depressions ("lebensspuren") formed by unknown organism.
E&F, Silty mud (compass cloud reveals muddy nature). Note scour lineations
(arrow indicates probable current direction toward south) in E. Abundant small
tubes of polychaete worms (Hyalinoecia) trending generally parallel to scour
lineations. Note also steep-sided depression of uncertain origin in E.

30

PLATE 10

^^■■^^^HflH

31

PLATE 11

Figs. A-F. — Station 23, outer shelf, east of canyon, 120-130 fms.

A-F, Shelly silty sand and sandy silt; vague, round crested, low amplitude inter-
ference ripple forms suggesting dominant movement toward the west. Patchy
distribution of fine shell hash. Subcircular depressions (arrows 1 in C and F)
formed by flat fish. Urophycid fish in B, C, E, and F. Plant-like forms (arrows 2
in C and F) may be sea-anemones.

32

PLATE 11

33

PLATE 12

Figs. A-F. — Station 24, canyon head, east wall, 250-280 fms.

A-D, Silty mud (cloud produced by compass indicates mud content); small linear
depressions, particularly noticeable in B, produced by crabs. Crab in A is
Geryon quinquedens Smith. Another unindentified crab in D (arrow). Subcircular
depressions probably formed by benthic fish. Linear depressions of unknown
origin in B. Worm tubes (arrows) projecting from bottom in C.

E&F, Bottom similar to above. Bottom-living flat fish (arrow in E) produce sub-
circular depressions in fine sediment.

34

PLATE 12

35

PLATE 13
Figs. A-B. — Station 25, canyon head, near axis, 480 fms.
Fig. C. — Station 26, outer shelf, west of canyon head, 62 fms.
Figs. D-F. — Station 27, outer shelf, west of canyon head, 71 fms.

A&B, Silt (cloud trailing compass indicates muddy nature of bottom); granular
nature of bottom (E) may be due to faecal pellets or reworked sediment clasts.
Tracks (probably in part crustacean) and fish (in A).
C, Shelly silty bottom ; two fish above bottom.

D-F, Shelly silty sand and sandy silt; low amplitude buried ripples (best seen in D)
indicate current toward WNW. Shells, concave-up and partially buried, are
concentrated in clusters. Coelenterate (arrow) upon shell in F.

PLATE 13

37

PLATE 14

Figs. A-F. — Station 28, upper slope, west of canyon, 140-160 fms.

A-F, Silty mud bottom (note cloud trailing compass in A and F). Abundant small
burrows, some of which may be due to worm tubes. Tubes of polychaete worms
(Hyalinoecia tubicola), most lying on bottom and some projecting obliquely (see
D center), common throughout station; note alignment of tubes in B and C.
Bottom-living flatfish of the type seen in D may be responsible for wavy tracks
("fin tracks", arrow 1 in A and E) and subcircular depressions ("fish-nest",
arrow 2 in F). A canceroid crab occurs in the upper left corner of E (arrow 3).

38

PLATE 14

B

I)

t

■ "u-«

39

PLATE 15

Figs. A-F. — Station 29, upper slope, west of canyon, on small ridge, 150-180 fms.

A-C, Sandy silt bottom with some shell; poorly preserved interference ripple marks
in upper margin of A; burrows in B; subcircular "fish-nest" structures in A and
B probably produced by benthic fish; unidentified fish above bottom in B and C.
Canceroid crab and floating medusoid coelenterate (arrow) in C.
D&E, Shelly sandy silt bottom with patches of subrounded granules, pebbles and
cobbles (See D, north of compass vane). Poorly preserved, low amplitude ripple
marks in D. Abundant Hyalinoecia tubes in E. Canceroid crab in D. Small eel
in E (arrow).

F, Bottom similar to above. Note abundance of polychaete tubes having a statistical
bimodal orientation.

40

PLATE 15

/

J

41

PLATE 16

Figs. A-F. — Station 30, near canyon axis, on slope, 598-610 fms.

A-C, Mud, largely clay bottom, as shown by clouds, some of which are caused by

flat fish (arrow 1 in B and C). These fish probably also produce paired curved

tracks (arrow 2 in A, B, and C). Burrows are also common. Granules visible in

B may represent faecal pellets.
D, Bottom, similar to above; obscured by suspended sediment. Note four eels.
E&F, Bottom similar to above; close-up view reveals granular texture (faecal

pellets?), depressions (fish?), paired tracks (arrow in F), and abundant burrows.

42

PLATE 16

/

43

PLATE 17

Figs. A-F. — Station 31, upper slope, east of canyon, 200-235 fms.

A-C, Mud, largely clay, bottom; local shell concentrations (A and C). Burrows

and semi-circular depressions common; sea-anemones are present; crab (Geryon

sp.) in C. Note small polychaete worm tubes in A and B, and rat-tail (Macrourid)

fish in A.
D-F, Bottom similar to the above; close-up view reveals abundance of tracks and

trails ("lebensspuren") some produced by fish and crustaceans.

44

PLATE 17

45

PLATE 18

Figs. A-F. — Station 32, slope, cast of canyon, 530-550 fins.

A-F, Muddy, largely clayey, bottom (note sediment clouds in A and B). Bottom
entirely covered by tracks and trails ("lebensspuren") and burrows. Paired track
(arrow in B, C, and D) are probably produced by bottom-living fish. Shrimp
resting on bottom in B and Macrourid fish swimming in F. Starfish in lower left
corner of A. Irregular muddy cloud in E probably produced by burrowing
organisms.

46

PLATE 18

47

PLATE 19

Figs. A-F. — Station 33, slope, near canyon axis, 680-750 fms.

A-F, Muddy, largely clayey, bottom (note sediment trailing and clinging to
compass in A and D). Bottom entirely covered by tracks and trails ("lebens-
spuren") and burrows. Note unidentified fish in E and sea urchins in E and F.

48

PLATE 19

49

PLATE 20

Figs. A-F. — Station 34, mid-slope, on Nyckel Ridge south of canyon, 610-625 fms.
A-F, Muddy, largely clayey, bottom (see sediment clouds in A, B, and F). Granular
texture, well developed in A, D, and E, may be produced by faecal pellets or
muddy clasts. Large steep-sided depressions of unknown origin in lower part of
E. Subcircular shallow depressions ("fish-nest" type) are common (see arrow
in D) and probably produced by benthic flat fish (see C and D). Sea-spider
(Colossendeis sp.) present (arrow 2) in D. Large dark circular object in F
may be a sea urchin. Note also probable Macrourid fish in F.

50

PLATE 20

/

51

PLATE 21

Figs. A-F. — Station 36, lower slope, south of Nyckel Ridge, 810-815 fms.

A-F, Muddy, largely clayey, bottom (see clouds in A and B). Granular texture,
particularly apparent in C and E, may be produced by faecal pellets or sediment
clasts. Halosaur fish, such as that in B, may produce linear tracks of the type
shown in B and C (arrow). Burrow in lower left corner of E. Sediment clouds
in center of F (arrow) may be produced by burrowing organisms. Sea urchin
is present in D.

52

PLATE 21

53

PLATE 22

Figs. A-F. — Station 37, on lower slope, on Nyckel Ridge south of canyon, 725-745 fms.
A-F, Muddy, largely clayey, bottom (see clouds in A and B). Granular texture,
apparent in E, may be produced by faecal pellets or sediment clasts. Burrows are
common; large steep-sided depressions of unknown origin in D (arrow). Elasi-
podid holothurian (arrow 1) and probable faecal remains (arrow 2) in C. Morid
fish and eel in D and sea urchins in D and F.

54

PLATE 22

55

PLATE 23

Figs. A-F. — Station 37-A, lower slope, near canyon axis, 820-900 fms.

A-F, Silty mud bottom (see cloud in D). Local concentration of large elongate
granules (arrow 2 in A, B, C), are probably faecal pellets of worm-like orga-
nisms (arrow 1 in A, B, E). Burrows and mounds are present; small worm
tubes (?) (circled in D) heel over in same direction (towards north). Ophiuroid
brittle stars (?Ophiomusium) are common; sea spider (Colossendeis sp.) in F
(arrow 3) ; eel in E.

56

PLATE 23

57

PLATE 24

Figs. A-P. — Station 38, lower slope, north of canyon, 695-735 fms.

A-F, Soft silty mud bottom (see clouds in A, D, and E). Bottom covered by
numerous tracks, trails and burows. Morid fish in A, B, and hagfish or eel in C,
and Lalosaur in D together with sea urchins (in A and B) are probably re-
sponsible for some of the bottom markings. Tube of polychaete worm (circled
in E) projecting from bottom. Present bottom current activity negligible.

58

PLATE 24

^

59

PLATE 25
Figs. A-C. — Station 39, lower slope, north of canyon, 1000-1050 fms.
Figs. D-F. — Station 41, lower slope, Nyckel Ridge south of canyon, 925-935 fms.

A-C, Muddy, largely clay, bottom covered by resting traces of brittle stars (arrow
in C) and deep burrows. Bladder-like organism in upper A (arrow) is probably
an elasipodid holothurian.
D-F, Silty mud bottom (cloud in D), slightly undulatory, covered by resting
traces of brittle stars. Large, steep-sided depression of unknown origin (E),
some of them 25 cm. in diameter, indicate cohesive nature of bottom. Subtle
east-west ripple crest orientations in E and F suggest possible north-south bot-
tom current movement. Probable worm-like organism (arrow) in upper part
of F.

60

PLATE 25

'

/

>

61

PLATE 26

Figs. A-F.— Station 42. lower slope, south of Nyckel Ridge, 990-1200 fms.

A-F, Silty muddy, slightly undulatory, bottom (see cloud in A) covered with
resting traces of brittle stars, mounds, and burrows, tracks and trails. Sub-
circular rings of small depressions in B (arrow) may be sunstar resting trace.
Some depressions may also be produced by sea urchins (in A, B, and C).
Possible holothurian or worm in D.

62

PLATE 26

63

PLATE 27

Figs. A-F. — Station 43, upper rise, Nyckel Ridge south of submarine valley, 1190-1215

fms.

A, Margin of fractured rock ledge on a slope. Main fracture direction ENE-WSW.
Rock outcrop, possibly of consolidated sandstone, is at least 15-20 cm. thick.
Fractures resemble joint pattern, possibly opened during slide and emplace-
ment of rock mass. Rock seems to be resting on flat sandy bottom (right of
photo).

B-D, Sand bottom in front of rock ledge shown in A, with numerous angular
blocks of well jointed rock broken off ledge. Note appearance of in situ rupture
of rock (arrow in C). Blocks resting on sand rippled by currents moving
towards NW. Dark pebbles are also noted near blocks and in ripple troughs.
Ophiuroid brittle stars, eel and Macrourid fish in D.

E&F, Sandy gravel bottom locally covered with silt as shown by clouds. Dark
pebbles and subrounded cobbles. Unidentified fish, brittle stars and regular sea
urchins (arrow) present in F.

64

PLATE 27

\

i

/

65

PLATE 28

Figs. A-F. — Station 43, upper rise, Nyckel Ridge south of submarine valley, 1190-1215

fms.

A, Broad outcrop of consolidated sediment veneered by silt (see cloud). Brittle
star indicates scale.

B-D, Rippled sand (current towards NW) carrying patches of dark pebbles, cob-
bles, and occasional larger angular blocks of rock, similar to that in Plate 27.
Blocks appear to have broken in situ (arrow in B). White circular objects in
left of C and D may be regular sea urchins; ophiuroid brittle stars in C and D.

E&F, Sandy gravel bottom veneered by silt (cloud in F) with occasional cobbles.
Pebbles appear to be relatively well-sorted suggesting current activity. Brittle
star in top of E partially covered by cobble. White specks in F may be sea
urchins.

66

PLATE 28

%

67

PLATE 29

Fies. A-C. — Station 44, upper rise, immediately south of submarine valley, 1185-1200

fms.

Figs. D-F.— Station 45, upper rise, north of submarine valley, 1190-1200 fms.

A-C, Silty mud bottom (cloud in A) with burrows, low mounds, trails and tracks.

Moving ophiuroid brittle star (arrow in C) and regular sea urchins in B.
D-F, Clayey bottom (cloud in E) entirely covered with tracks, trails, resting
places, and burrows. Granular appearance possibly due to faecal pellets or
sediment clasts. Aspidochirotid holothurian (arrow 1) and Morid fish (arrow 2)
in D.

68

PLATE 29

1

69

PLATE 30
Figs. A-C. — Station 46, upper rise, north of submarine valley, 1290-1300 fms.
Figs. D-F. — Station 47, upper rise, south of submarine valley, 1340 fms.

A-C, Mud, largely clay, bottom with small depressions and burrows. Note large
darker ovate patches. Bladder-like object in A (arrow 1) is probably an Elasi-
podid holothurian. Unidentified sea-star or crinoid (arrow 2) in A. Linear trail
in B. Ophiuroid brittle stars near base of C; also small worm tubes or small
holothurians (circled) projecting from bottom.
D-F, Silty mud bottom, slightly undulatory, covered by tracks, trails and burrows.
Small worm tubes or small holothurians projecting from the bottom (circled in
E and F) trend toward the east, suggesting current moving in that direction.
Regular sea urchins in all three photographs.

70

PLATE 30

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71

PLATE 31
Figs. A-C. — Station 48, upper rise, on Nyckel Ridge, 1300 fms.
Figs. D-F. — Station 49, upper rise, south of Nyckel Ridge, 1410 fms.

A-C, Gravelly, sandy mud with local concentrations of subrounded cobbles with
diameters up to 40 cm. Trace of ripple crest orientation of 035°-215° in B.
Ripples are buried under a veneer of silt. Regular sea urchins are represented
by white specks in all photos.
D-F, Sandy mud bottom with gravel. Note organism-encrusted boulder between
arrows (approximately 1 m in length) on left margin of F. Sublinguoid ripple
marks indicate current movement towards SSW. Elasipodid holothurian in D.

72

PLATE 31

73

PLATE 32
Figs. A-C. — Station 50, upper rise, immediately south of submarine valley, 1420 fins.
Figs. D-F. — Station 51, upper rise, north of submarine valley, 1400-1405 fins.

A-C, Sandy silty mud bottom (cloud in A). Interference ripple marks with domin-
ant trend showing current movement towards SSW. Plant-like organisms
(coelenterates?) depicted by arrows in A.
D-F, Mud, largely clay, bottom (cloud in D) covered with large tracks (arrow 1
in F) and some burrows and mounds. Asteroid seastars in D and E; plant-like
organisms (coelenterates?) in E and F (arrow 2).

74

PLATE 32

I

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d

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75

PLATE 33

Figs. A-B. — Station 52, outer part of upper rise, north of submarine valley, 1460-1465

fms.

Figs. C-F. — Station 53, outer part of upper rise, adjacent to submarine valley, 1506

fms.
A&B, Silty mud bottom (cloud in A) with possible pebbles or unidentified orga-
nisms (arrow 1 in A and B). Bottom covered with burrows, mounds, tracks,
trails, and resting places of brittle star (arrow 2 in A) and sun-star (arrow 3
in A). Elasipodid holothurian narrowly avoids striking the compass in A.
C-F, Silty mud bottom, slightly undulatory, with burrows and circular sun-star
imprints. Track of unknown origin in F.

76

PLATE 33

1

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1

77

PLATE 34

Figs. A-F. — Station 54, outer part of upper rise, south of submarine valley, 1490 fms.
A-E, Silty mud bottom (cloud in A), slightly undulatory. Tracks, trails, sunstar

resting trace, burrows, and mounds common.
F, Evidence of deep ocean bacchanaliu at about 1500 fms.

78

PLATE 34

79

IV. RESULTS

General

A total of 1243 photos were taken at the
fifty-four stations shown on Fig. 3. Of these,
approximately two thirds, or about 800 frames,
were close enough to the bottom to show some
evidence of lithology, current activity or or-
ganisms. About one sixth or 200 of the frames,
generally taken close to the bottom (within 1
fathom) could be categorized as good to excel-
lent. The photographic information collected at
each station is summarized in Table II.

This table includes the following data for
each station studied : film roll and frame num-
ber, quality of photographs, bottom surface
area covered, bottom textural types, ripple
marks and other current indicators, organisms,
and other pertinent observations. Selected rep-
resentative photographs of the bottom at most
of the stations are presented in Plates 1 to 34.
A brief summary highlighting sediment tex-
ture, inferred bottom current directions, and
organisms recorded on film is presented below.
Figures 7 to 10 have been compiled by plotting
data summarized in Table II.

Sediment Texture

The contoured regional distribution of major
sediment textural types (sediment grain size
mixtures) is shown in Fig. 7. The textural
terms used are those employed by sedimentolo-
gists (Pettijohn, 1957). Textural interpreta-
tions were verified by coring, where possible,
and by comparison with sediment notations of
Stetson (1949) and Hathaway (1966, 1967).
Coarse to medium sand occurs near the outer
shelf margin and the head of the Wilmington
Canyon to depths somewhat in excess of 50
fms. Sandy silt and silty sand actually drapes
the shelf edge and uppermost continental
slope. This material also fills the upper canyon
head and extends as a tongue down the axis to
about 500 fms. Greater photographic coverage
in the canyon could indicate that this tongue
actually extends further downslope. Silt and
clay admixtures (material finer than 0.0625

mm) increase and the relative percentage of
sand (0.0625-2.0 mm) decreases substantially
below 50 fathoms. However, local concentra-
tions of sandy sediment are noted at greater
depths, particularly on the Nyckel Ridge (Sta-
tions 43, 48, 50 and 52) , to about 1500 fms.

Pebble and cobble-sized material (coarser
than 2.0 mm) appear to be concentrated in
three areas. A tongue of coarse material on the
steep east wall of the canyon head extends
from the shelf edge to depths exceeding 300
fms. Boulders, some exceeding 1 m. in diame-
ter, occur near the axis at Stations 13 and 17.
An isolated gravel location (Station 29) was
encountered on the southwest canyon wall at a
depth of about 150 fms. Gravel, with sand and
mud, also occur on the upper rise near the Ny-
ckel Ridge at Station 49 and north of the can-
yon axis at Station 52.

Below about 100 fms silt and silty mud cov-
ers the canyon proper and the continental slope
and rise. The slope east and north of the can-
yon tends to be covered with soft clayey mud.
Stiff clay is noted at several deep stations par-
ticularly those on or near the Nyckel Ridge in-
cluding Station 41 at 930 fms. Small muddy
lumps of granule size in silt and clay sedi-
ments, common in some slope and rise stations,
are probably of organic origin and may be fae-
cal pellets (Table II).

A rock outcrop was noted at Station 43 on
the Nyckel Ridge at the base of the slope. This
large, parallel-bedded ledge is more than one
meter thick and displays a series of distinct
linear fractures (Plate 27, fig. A). Angular
rock fragments broken from the leading edge
of the ledge lie at the base of the outcrop
(Plate 27, figs. B-D) . The presence of a thin ve-
neer of silt on the rock slabs in shown in Plate
28 (fig. A).

Inferred Bottom Currents (Neocurrents)
and Sediment Movement

The photographic survey makes it possible
to detect the evidence of recent bottom current

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activity (neocurrent patterns) and to infer the
dominant current trends in the area of study.
Most of this evidence is derived from an exam-
ination of current-formed sedimentary struc-
tures, principally ripple marks, and the atti-
tude of certain marine organisms, principally
worm tubes, on the compass-orientd photo-
graphs (Table II). The paterns of dominant
current movement in the Wilmington Canyon
and adjacent continental shelf, slope and rise
are depicted on Fig. 8.

The form of ripple marks (straight, sinuous,
interference types) and the orientation of dom-
inant crests were recorded, and the direction of
steeper faces was measured wherever possible.
The vertical position of the camera and slight
oblique illumination employed, however, made
this determination impossible in some in-
stances. A two-directional trend is depicted in
those cases where symmetrical ripple-marks
are present or where the appearance of sym-
metry does not allow interpretation of the
sense of current transport. The mean value of
current direction or trend has been determined
for each station ; this value, in some cases, rep-
resents the orientation of current patterns
measured over as much as two miles of sea
floor. In several cases the large number of pho-
tos obtained over an extensive distance re-
quires that the data be grouped into two or
more sub-stations. Stations 7 and 8, for in-
stance, extending from the shelf margin into
the canyon head, display several mean vectors
(Fig. 8). Two transport direction are also de-
picted at those stations where interfering
groups of ripple marks differ in orientation by
more than 30°

Ripple marks on the shelf and upper slope
tend, in general, to be asymmetrical, straight
to slightly sinuous and possess sharp to some-
what rounded crests. Two or more sets of
cross-cutting ripples are not infrequent at
shallow stations, but distinct cell-like interfer-
ence patterns have not been observed here. In-
terfering ripple-sets usually differ in dimen-
sions or form, and it is generally possible to
demonstrate that one set post-dates the others.
Ripples on deeper silty and mud bottoms tend
to be more sinuous and discontinuous with low
amplitudes and soft rounded crests. Many rip-
ples appear relatively fresh and are probably
of recent origin. A veneer of mud, however,

covering crests and partially filling troughs,
may be detected at some deeper stations.

Additional evidence of current transport is
obtained in a number of stations from the
alignment of shell debris or gravel, and of
worm tubes lying upon the bottom. Scour li-
neations and pockets are generally absent ex-
cept for Station 22 (Plate 10) in the canyon
axis and at Station 43 (Plate 28) at the base of
the slope. Similar scour lineation markings on
the continental slope have been reported by
Owen and Emery (1967, Fig. 15-4).

Direct evidence of prevailing near-bottom
current activity is provided by the preferred
orientation of worm-tubes that appear stalk-
like and project obliquely from the sea-bed to a
maximum height of 10 cm. These structures,
presumably geotropic in character, locally dis-
play a random orientation. More frequently
these tubes show a preferential alignment, i.e.,
a dominant sense of inclination, as if heeling
over in response to a current. It is assumed
that such an inclination is in a down-current
sense. This assumption is borne out at Station
29 where preferentially inclined worm tubes
and asymmetric ripples are associated (Plate
15).

The regional current transport pattern as in-
ferred from photographs is evidently a com-
posite one. Landward of the shelf edge cur-
rents flow uniformly towards the west both on
the shelf proper and in the canyon head. In a
small area northwest of the canyon (Stations 3
and 5) currents appear to flow towards the
south and southwest. Observation of large sand
waves and dunes to depths exceeding 50 fms
suggest that sedimentation on this outer shelf
may be active, not relict, at present.

Evidence of southerly current movement
down the canyon axis between 400 and 600 fms
is observed at Stations 22 and 30 (Plate 10).
Little evidence of current activity is noted on
the lower slope and adjacent parts of the upper
continental rise away from the canyon ; the
sea-floor in this area is one dominated by bio-
logical reworking of bottom sediments. A re-
newal of current activity on the outer sector of
the upper rise is noted at depths greater than
1400 fms; current flow at this depth tends to
be directed consistently towards the southwest
and south-southwest (Fig. 8).

86

Conspicuous current activity is also asso-
ciated with the Nyckel Ridge forming the
south (right) bank of Wilmington Canyon.
Water movement on the upper part of this
ridge appears to be directed up-slope (west and
west-northwest). A northerly current sense is
indicated on the more deeply submerged por-
tion of this ridge at depths of 1000 to 1200
fms. Additional evidence of current activity on
this outer ridge are provided by the observa-
tion of a firm bottom of stiff clay at Station 41.
Samples of similar lithology have been recov-
ered from this region by the Woods Hole
Oceanographic Institution (Sample 2109B, in
Hathaway, 1966) suggesting removal or non-
deposition of recent finegrained sediment in
this sector. Strong northwest-flowing currents
capable of moulding sand and gravel into rip-
ples are also noted on the Nyckel Ridge at Sta-
tion 43 (Plates 27. 28).

Benthic Organisms

Benthic organisms, like bottom currents, ap-
pear to modify bottom sediments in the Wil-
mington submarine canyon and adjacent areas.
The lateral distribution of the more important
groups of organisms detected in the photo-
graphic survey are shown on Figures 9 and 10.

Shell material forms a large part of the
coarse sediment fraction on the shelf edge at
depths less than 100 fms, particularly on the
northern and eastern margins of the canyon
head (Fig. 9). Shell material of coarse sand to
pebble size is often aligned in bands concen-
trated in ripple mark troughs. Many of the
shells, sometimes distinct enough to be recog-
nized as pelecypod valves of scallops and other
forms, lie concave up and are often partially
buried or filled with sediment. The shell con-
tent decreases from over 30 percent on sectors
of the shelf to about 1 percent at depths of
about 200 to 300 fms. Pelecypod valves of
probable shelf origin have, however, been en-

countered in cores collected in the canyon and
on the continental rise (Stanley and Kelling,
1968b, Fig. 8).

Echinoderms are also locally important on
the shelf and include starfish, sand dollars and
sea urchins (Fig. 9). Crabs and lobsters also
abound in this area (Fig. 10). This environ-
ment is one of high sand and shell content.
Crustaceans apepar to be more abundant in the
immediate vicinity of the canyon area than on
the adjacent slope.

The area covered by burrowing organisms
increases progressively at depths greater than
75 fms. Burrows, tracks, mounds, and other
forms of bioturbation are recorded at almost
every station below this depth, with the excep-
tion of Station 43 (Fig. 10). Pencil-like tubes of
polychaete worms [probably Hyalinoecia tubi-
cola (Muller)], a common form on the conti-
nental slope of northeast North America (Wig-
ley and Emery, 1967), are locally important.
Numerous forms of bathyal echinoderms (Fig.
10), including brittle stars and asteroid star-
fish, become important below depths of about
500 fms. These, as well as crabs and sea spi-
ders leave distinctive markings in the soft mud
bottom and otherwise modify the sediment as a
result of their movement and their feeding
habits.

Equally spectacular are bottom markings
produced by benthic fish (Fig. 9) ; these appear
to be most abundant on the slope between 100
to 1000 fms. The soft undulating mud at some
localities has been entirely moulded by fish
that form shallow depressions (resting-places
or "nests"), and by fin marks. Holothurians
are important because of the trails they make
and because of the abundance of their faecal
deposits which cover extensive areas of the
bottom (Table II). Coelenterates, including
sea-anemones and possible soft corals, are re-
corded at four localities but are generally less
common than the preceding forms (Fig. 10).

87

V. DISCUSSION

Most of the submarine canyons off the east
coast of the United States previously have been
regarded as relatively inactive so far as sedi-
mentary processes are concerned (Stetson,
1949; Shepard, 1965a, p. 327) because they
head far out on the shelf in deep water in tec-
tonically stable area. This contrasts sharply
with submarine canyons in other areas which
serve to funnel sediments from shelf areas to
the deep sea. Shepard (1965a, p. 322-323) lays
particular stress on supply of longshore-
drifted detritus to canyons heading close in-
shore on tectonically active borderlands, as in
the area off southern California. In those can-
yons, sediment is transferred from the head to
the deep-sea fans at their base by processes
which include slumping, creep, sand flows and
turbidity currents. The surface texture in the
vicinity of these Californian canyons appar-
ently reflects the present activity of the pro-
cesses outlined above although a thin cover of
'pelagic' mud occurs in areas more remote
from active channels (Shepard and Dill, 1966,
p. 68). A submarine canyon on the northwest
Atlantic margin. The Gully off Nova Scotia,
which has been described by Stanley (1967)
displays a spectrum of processes similar to
those observed in canyons on the Pacific mar-
gin.

In the Wilmington canyon area, the sum of
photographic observations shows that textural
types are more closely related to geographic
proximity to the canyon depression and other
major features of the slope than to depth per
se. However, the distribution of relatively fine-
grained bottom surface sediments in the prox-
imity of the Wilmington canyon (an observa-
tion also made by Stetson, 1949) and the abun-
dance of burrowing activity in all but the most
shallow portions of the canyon suggest a rela-
tively inactive role for sedimentation at the
present time. Similarly, the pattern of current
movement in the vicinity of the canyon, where
examined, shows only minor evidence of axial
transport (unlike more active canyons de-

scribed by Shepard, 1965b; Shepard and Dill,
1966; Ross, 1968 and others).

Photographic evidence, however, must be in-
terpreted cautiously in evaluating the role of
the Wilmington Canyon in Holocene (post-
Pleistocene to modern) sedimentation. It is im-
portant to note, for instance, that textural va-
rieties at the surface often conceal very differ-
ent sediment types just a few millimeters or
centimeters below the surface. An examination
of cores collected in the same areas as photo
Stations 33, 34 and 46 (Fig. 3) indicates that
the surface veneer recorded in bottom photo-
graphs is generally finer-grained than the sedi-
ment lying below it (Stanley and Kelling,
1968b). The textural pattern as mapped in
Figure 7 is thus a composite reflecting both re-
cent depositional activity and, locally, relict
(pre-Recent) sediment patterns. These local
pockets of relict sediment may represent areas
which are not receiving sediments at the pre-
sent time or they may indicate removal of the
veneer of recent sediment by erosion.

It is also important to note that the textural
map indicates only the most recent sediment
activity and masks the results of processes op-
erating in the recent past. Examination of the
bottom photographs suggests that, at present,
benthic organisms are reworking the sediment
cover over much of the slope and rise. Cores
show distinct laminations of somewhat coarser
sediment below a mottled uppermost sediment
veneer. This indicates that at most localities
periods of active deposition have alternated
with quieter periods (perhaps like the present)
when the entire sediment horizon is reworked
by bottom-living organisms.

The hypothesis that sedimentation in the
Wilmington submarine canyon has been active
within the recent past, and perhaps even today
on a local scale, is supported by several obser-
vations :

(1) The present study indicates that there

88

is strong current activity on the outer shelf in
this region (see Fig. 8). The siting of the Wil-
mington Canyon is such that sediment being
transported westward across the outer shelf
(in accord with the direction of non-tidal bot-
tom drift noted by Bumpus, 1965, Fig. 5) would
be intercepted by the canyon head. The tongues
of gravel, coarse sand and shell debris which
extend down the eastern flanks of the canyon
head (Fig. 7) evidently result from this process
of entrapment, since materials of comparable
grade are lacking on the sheltered western
walls. The first prerequisite for active canyon
sedimentation — a continuing supply of sedi-
ment to the head — is thus fulfilled.

(2) A narrow tongue of silty sand extends
down the canyon axis to a depth of about 500
fms suggesting down-slope movement of coar-
ser detritus, at least to this depth, at the pre-
sent time.

(3) While clay muds cover the continental
slope and upper continental rise in areas re-
mote from the canyon, the distribution of silt
follows the trend of the major depressions as-
sociated with Wilmington canyon (compare
Figs. 1 and 7). The pattern of silt distribution
closely resembles that discovered by Stanley
(1967, Figs. 7 and 8) in The Gully Canyon.

(4) Patches of gravel and sand presently
exposed on the upper rise may be relict depos-
its swept clear of recent mud by the deep-sea
currents detected in their vicinity. On the
other hand, they may indicate active, if peri-
odic, supply of coarse detritus to the upper rise
via the Wilmington Canyon complex. Ample
evidence of such periodic influxes of debris
within the recent past is provided by the pres-
ence of sand and shell debris in cores (Stanley
and Kelling, 1968b, Fig. 8).

One point is clear : the supply of coarse shelf
sediment moving toward the west and, thus,
toward the head of the canyon is such that
most of the material must be transferred
quickly to the deep sea. Were it not, the head
would soon be filled.

The fine-grained veneer that floors much of
the area of the slope and rise is being contrib-
uted, in part, by a rain of pelagic material set-
tling to the bottom. The origin of this material
is unknown at present. Muds cou i originate

from deposition of suspended matter concen-
trated in the water column by deep turbulence.
This nepheloid layer on the slope and rise
north of the Wilmington Canyon has been de-
scribed by Ewing and Thorndike (1965). Geos-
trophic contour bottom currents of the type
recognized at the base of the Atlantic margin
by Heezen et al. (1966) and Schneider et al.
(1967) may also play an important role in the
transport and deposition of sediments.

Evidence from bottom photographs of south-
west and south-southwest flowing currents on
the outer sector of the upper rise are compati-
ble with the geostrophic contour patterns re-
corded by these other workers. However, in
this study area, flow also occurs at a level on
the upper continental rise, which Schneider et
al (1967, p. 358) regard as a tranquil, current-
free region. Strong, northwest-flowing cur-
rents that are capable of moulding sand and
gravel at station 43 (Plate 28) may form part
of an eddy system developing counter to the
main Western Boundary Under Current. The
location of this eddy is probably controlled, in
part, by the presence of the southeast-north-
west trending Nyckel Ridge. Observation of
this ridge shows that bottom currents are ca-
pable of moving material of fine to coarse sand
grade and that they may well play an impor-
tant role in modifying the dispersal pattern of
sediment emanating from the Wilmington Can-
yon on the lower slope and rise.

At present, the Nyckel Ridge bounding Wil-
mington Canyon on its south side forms an im-
portant locus of current activity and of prob-
able slope instability, i.e. slumping and gravita-
tional gliding, perhaps of the type described by
Rona and Clay (1967) and Uchupi (1968). The
occurrence of large angular slabs of rock with
talus at Station 43 suggest either active ero-
sion of outcropping rock as described by
Schneider et al. (1967, p. 358) or slumping and
sliding of large rockmasses off the adjacent
Nyckel Ridge onto a sand-silt bottom. Evidence
for displacement of these blocks is provided by
a series of linear fractures in the rock ledge
proper (Plate 27). The general trend of main
fractures affecting these rocks is N50°E, i.e.
parallel with local isobaths. The breaks are not
unlike crevasses in glaciers or in areas of in-
cipient avalanches such as steep snow-covered

89

hills. The rock mass illustrated in Plate 27 rep-
resents an allochthonous slab moved into place
at this locality.

The present photographic investigation, cou-
pled with an earlier subbottom survey during
RoS, indicates that the Nyckel Ridge is not
simply a deep-sea levee (Stanley and Kelling,
19fi8a). This topographic high developed as a
structural feature and serves as an important
internal source of sediment as a result of expo-
sure to bottom current activity, erosion, and
slumping. In effect, it plays a dominant role in
intrabasinal sedimentation.

Evidence gathered on the basis of the photo-
graphic study does not allow a categorical an-
swer to the problem of the Wilmington Can-
yon's contemporary funneling role. An evalua-
tion of the past present functions of the canyon
in the context of deep sea sedimentation off the
Atlantic margin clearly requires further inves-
tigation. A comparison of the dominant pat-
terns in the Wilmington Canyon with those of
adjacent features including Baltimore, Wash-
ington, and Norfolk Canyons should eventually
lead to the creation of a sedimentation model
for canyons of this type.

90

VI. ACKNOWLEDGMENTS

We would like to thank: the U.S. Coast
Guard, for providing ship-time and facilities
and making the operation of this investigation
possible; the U.S. Coast Guard Oceanographic
Unit, Washington, D.C., for coordinating the
program ; the Captain, officers and men of the
USCGC ROCKAWAY (WAGO 377), for their
support in the work at sea ; Messrs. Robert K.
Oser and Martin G. Fagot, Naval Oceano-
graphic Office, Washington, D.C. for lending

and operating a camera rig which resulted in
much of the information presented in this
paper ; Mr. H. Sheng, for compilation of bathy-
metric data; and the Smithsonian Institution
Research Foundation for funds in support of
this continuing program. This work was un-
dertaken while Kelling was an NRC Visiting
Research Associate at the Smithsonian Insti-
tution, on leave from the University of Wales,
Swansea, Great Britain.

91

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tinental Shelf. Summary of Investigations conducted
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66-13, p. 158.

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Edgerton, H E., 1967. The instruments of deep-sea
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47-54.

Ewing, M. and E. M. Thorndike, 1965. Suspended
matter in deep ocean water. Science, v. 147, p.
1291-1294.

Hathaway, J. C, 1966. Data file. Continental margin
program, Atlantic coast of the United States, Vol. I,
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, 1967. Data file, Continental margin program,

Atlantic coast of the United States, Vol. I, Sample
collection data, Supplement I. Woods Hole Oceanogr.
Institution Ref. 67-21, 108 p.

Heezen, B. C, C. D. Hollister and W. F. Ruddiman,
1966. Shaping of the continental rise by deep
geostrophic contour currents. Science, v. 152, p.
502-508.

Hersey, J. B., 1967. The manipulation of deep-sea
cameras, in Deep-Sea Photography (J. B. Hersey,
Ed.). The Johns Hopkins Press, Baltimore, p. 55-67.

Johnson, D. W. 1939. The Origin of Submarine Can-
yons. Columbia University Press, New York, 126 p.

Kuenen, Ph. H., 1950. Marine Geology. John Wiley
and Sons, Inc., New York, p. 485-526.

Lawson, A. C, 1893. The Geology of Carmelo Bay.
Bull. Univ. Calif. Dept. Geology, I, 59 pp.

Owen, D. M. and K. O. Emery, 1967, Current markings
on the continental slope, in Deep-sea Photography
(J B. Hersey, Ed.). The Johns Hopkins Press, Balti-
more, p. 167-172.

Pettijohn, F. J., 1957. Sedimentary Rocks. Harper &
Sons, N.Y. 718 p.

Pruvot, G., 1894. Essai sur la topographie et la con-
stitution des fonds sous-marins de la region de
Banyuls, de la plaine du Rousillon au Golfe de Rosas.
Arch. Zool. Exp. Gen., v. 2, p. 599-672.

Rona, P. E. and C. S. Clay, 1967. Stratigraphy and
structure along a continuous seismic reflection pro-
file from Cape Hatteras, North Carolina, to the
Bermuda Rise. Jour. Geophys. Research, v. 72, p.
2107-2130.

Ross, D. A., J.V.A. Trumbull and C. D. Hollister, 1968.
Geologic observations in Corsair canyon from DSRV
Alvin (Abstract). Geol. Soc. America Northeastern
Section, Program 3rd Ann. Meeting, Washington,
D.C., p. 52.

Schneider, E., P. J. Fox, C. D. Hollister, H. D. Need-
ham and B. C. Heezen, 1967. Further evidence of con-
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and Planetary Sci. Letters, v. 2, p. 351-359.

Shalowitz, A. L., 1930. Slope corrections for echo sound-
ings. U. S. Coast and Geodetic Survey Spec. Pub.
No. 165.

Shepard, F. P., 1963. Submarine canyons, in The Sea
(M. N. Hill, Ed.). Interscience Publishers, New
York, p. 48-506.

, 1965a. Importance of submarine valleys in

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Oceanography, v. 3 (M. Sears, Ed.) Pergamon Press,
Oxford, p. 321-332.

, 1965b. Submarine canyons explored by

Cousteau's Diving Saucer, in Submarine Geology and
Geophysics (W. F. Whittard and Bradshaw, Eds.)
Butterworth, London, p. 303-311.
, and R. F. Dill, 1966. Submarine Canyons and

other Sea Valleys. Rand McNally, Chicago. 381 p.

Stanley, D. J., 1967. Comparing patterns of sedimen-
tation in some modern and ancient submarine can-
yons. Earth and Planetary Sci. Letters, v. 3, p.
371-380.

, and G. Kelling, 1968. Interpretation of a levee-
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-, 1968b. Sedimentation patterns in the Wilming-

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Veatch, A. C. and P. A. Smith, 1939. Atlantic sub-
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7, 101 p.

Wigley, R. L. and K. O. Emery, 1967. Benthic animals,
particularly Hyalinoecia (Annelida) and Ophio-
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Baltimore, p. 235-249.

92

Table I. Station positions and depths on USCGC ROCKAWAY-SMITHSONIAN Cruise (RoS:).

(December 4-10, 1967)

Station
Number

Beginning of station

End of station

Latitude

Longitude

Depth in fathoms

Latitude

Longitude

Depth in fathoms

1

38°31'27.0"

73°27'50.7"

46

38°31'9.5"

73°28'19.7"

51

2

38°31'20.6"

73°29'33.8"

45

38°30'39.7"

73°29'48.0"

74

3

38°31'21.5"

73°31'39.2"

36

38°30'58.8"

73°31'51.5"

39

4

38°29'58.3"

73°32'15.0"

47

38°29'22.0"

73°32'18.0"

52

5

38°29'44.0"

73°31'31.4"

60

38°29'12.8"

73°31'9.4"

107

6

38°29'46.4"

73°30'33.7"

114

38°29'4.7"

73°30'48.6"

129

7

38°29'44.1"

73°28'44.7"

59

38°29'11.7"

73°29'12.7"

89

8

38°29'3.2"

73°29'6.2"

131

38°28'18.3"

73°29'31.3"

110

9

38°28'22.6"

73°30'57.2"

214

38°27'15.8"

73°31'47.7"

195

10

38°28'50.8"

73°32'37.7"

59

38°28'22.5"

73°33'8.8"

57

11

38°28'22.5"

73°33'22.7"

54

38°27'59.3"

73"33'28.6"

58

12

38°28'6.0"

73°33'43.8"

52

38°27'41.1"

73°34'5.0"

58

13

38°27'13.4"

73°31'11.6"

278

38°26'32.6"

73°32'4.2"

258

14

38°28'16.1"

73°30'0.7"

124

38°27'36.2"

73°29'53.9"

92

15

38°27'26.0"

73°29'7.9"

76

38°27'16.4"

73°29'36.8"

63

16

38°26'44.3"

73°29'44.1"

65

38°25'41.9"

73°29'50.6"

168

17

38°26'8.2"

73°31'44.1"

240

38°24'46.0"

73°32'41.4"

380

18

38°26'6.1"

73°34'51.4"

68

38°25'33.1"

73°35'19.6"

76

19

NO

STATION

20

38°24'43.2"

73°36'57.2"

57

38°24'5.5"

73°36'25.4"

62

21

38°24'35.5"

73°32'57.2"

355

38°24'18.4"

73°34'6.4"

160

22

38°24'38.2"

73°31'19.8"

430

38°23'30.5"

73°32'11.7"

391

23

38°24'5.9"

73°27'5.5"

80

38°23'18.8"

73°2fi'51.5"

156

24

38°23'54.7"

73°29'35.9"

243

38°23'14.6"

73°29'23.8"

302

25

38°23'29.1"

73°31'5.5"

460

38°23'17.3"

73°31'52.6"

480

26

38°22'50.4"

73°36'9.6"

62

38°22'19.1"

73°36'16.0"

62

27

38°20'51.7"

73°35'43.1"

71

38°20'10.0"

73°36'0.5"

73

28

38°18'47.5"

73°35'56.8"

128

38°17'46.9"

73°36'16.0"

165

29

38°19'48.2"

73°33'10.9"

127

38°19'5.0"

73°33'42.0"

194

30

38°21'10.5"

73°29'32.7"

620

38°21'49.2"

73°30'36.2"

595

31

38°22'51.0"

73°26'21.8"

195

38°22'42.0"

73°27'4.0"

247

32

38°21'30.6"

73°23'22.9"

518

38°20'32.7"

73°24'30.4"

575

33

38°19'55.1"

73°25'37.8"

772

38°19'6.4"

73°26'14.9"

654

34

38°17'33.1"

73"28'17.0"

602

38°18'0.7"

73°27'52.4"

640

35

38°18'12.8"

73°27'52.2"

648

38°15'55.8"

73°30'15.9"

566

36

38°11'58.8"

73°28'27.5"

810

38°09'47.1"

73"36'23.4"

817

37

38°16'17.0"

73°34'05.7'

795

38°15'28.7"

73°35'35.1"

715

37A

38°17'46.4"

73°22'36.2"

909

38°17'31.4"

73°24'26.5"

808

38

38°20'35.8"

73°20'48.1"

786

38°20'30.1"

73°22'24.2"

692

39

38°19'7.3"

73°15'06.7"

1050

38°18'42.4"

73°16'53.1"

1000

40

38°15'49.8"

73°17'17.8"

1030

38°15'51.0"

73°19'49.6"

964

41

38°13'46.9"

73°18'08.1"

940

38°13'35.8"

73°19'24.3"

903

42

38°10'58.7"

73°19'18.1"

1029

38°10'48.6"

73°20'29.6"

990

43

38°10'47.0"

73°06'36.3"

1176

38°10'20.7"

73°07'24.8"

1222

44

38°14'24.1"

73°07'12.9"

1177

38°15'38.3"

73°07'46.6"

1208

45

38°18'48.5"

73°06'33.4"

1200

38"19'32.7"

73°07'24.5"

1181

46

38°19'19.5"

72°59'46.8"

1285

38°19'11.7"

72°59'22.1"

1308

47

38°12'41.0"

72°59'54.5"

1338

38°12'47.4"

72°59'32.2"

1340

48

38°10'15.7"

72659'32.3"

1295

38°09'31.8"

72°58'41.5"

1325

49

38°07'6.2"

72°54'9.2"

1408

38°07'3.6"

72°53'07.9"

1413

50

38°11'57.9"

72°53'13.3"

1417

38°11'36.6"

72°52'26.5"

1421

51

38°18'21.4"

72°51'43.7"

1395

38°17'18.8"

72°51'02.0"

1408

52

38°18'47.9"

72°41'0.7"

1457

38°17'22.8"

72°40'28.4"

1470

53

38°12'59.5"

72°42'08.3"

1506

38°11'22.5"

72°42'50.4"

1507

54

38°07'37.6"

72°44'34.7"

1495

38°05'16.5"

72°45'20.8"

1483

93

Table II. Summary of data from photographic investigation in the Wilmington subma

Film

Photo

Sediment

Ripple Marks

Oriented

Data

Quality

_ Type

Worm

Qjp = Dominant

type

H := Heeling

_

Type

Inferred

Wave

Amplitude

direction

a*6!

A =

Asymmetric

Current

Length

(where

A = Alignment

s =

Symmetric

Movement

(in cm.)

available)

trend

"c-8

®

— Dominant

(Mean

(in cm.)

5e

S-5

type

direction

°6

>l

or trend at

RJ

s

station)

V

s

a

u
u

•9 °

II

O a>

+

0)

55

a

3

B

3
Z

o

16

bo a

>

■a
c

43
W

3

'3

CO

3
O
3
C

s
at

a

V

V

s

Ul

a

fc.Cn

K<

u

w

2

w

M

c

1

l

192-227

Poor to Moderate

>4

®

X

(£3

A,S

to 285°

25-35

2

l

260-305

Very Poor 1

>4

(as)

A

to 200° '

3

l

337-355

Poor to Good

1-4

^

X

T^v

A,S

to 235° 2

12.5-50

2.5-10

4

l

391-409

Poor to Moderate

2-4

©

X

X

to 275°
to 185°

17.5-30

5

1

451-472

Poor

1-4

®

®

@J

s

134°-314°

17.5-50

4.2-10

6

1

536-550

Poor to Good

<l-4

X

@

to 240°

12.5-30

1.25-5

to 270° •

7

1

606-634

Moderate to Excellent

1-4

X

®

A

A

A.S

to 253° 2

to 285° 3

to 252° i

15-55

1.25-7.5

8

2

680-716

Moderate to Excellent

<l->4

X

®

A,S

A.S

A.S

to 283° 2

12.5-25

9

2

746-762

Moderate to Excellent

<1

X

®

A

to 260° *

10-17.5

10

2

774-789

Poor to Excellent

<l-2

X

A

to 279°

15-20

2.5-3.75

U

2

825-861

Poor to Moderate *

2-4

X

®

A

to 285°
165°-345°

17.5-25

1.25-2.5

12

2

891-904

Poor to Excellent

<l-4

X

©

®

A

to 258°

15-20

13

2

939-963

Moderate to Excellent

<l-2

Xi

X

®

H : to 270°

14

2

001-016

Moderate to Good

1-4

Xi

®

®

®

S

to 318°

17.5-25

15

3

050-076

Moderate to Excellent

<l-4

Xi

®

®

A

to 281°

12.5-20

1.25-2.5

16

3

125-161

Good to Excellent

<l-2

X

®

S

f

to 272°

12.5-17.5

0.65-1.25

H : to 345°

17

3

188-189

Poor

1-2

Xi

Qy

95°-275°

20-25

18

3

242-294

Moderate to Excellent

1-4

X

(X) >

A.S

to 271°

10-22.5

2.5-3.75

19

NO

STATION

20

3

294

Moderate

2-4

X

f

A

to 250°

25

21

3

332

Moderate

1-2

22

3

369-406

Poor to Excellent

<l-4

Xi

to 180° 2
to 254°

H : to 180°

23

4

473-499

Moderate to Good

<l-2

X

?

S.A

112°-292°

20-37.5

1.25-3.75

24

4

534-561

Moderate to Excellent

<l-2

S

097°-277°

15

1.25

H: toWNW

25

4

601-605

Good

<1

Xi

S

30

26

4

678-698

Poor to Moderate

1-4

X

®

A

to 268°
070°-250°

17.5-20

1.25-2.0

27

4

728-755

Moderate to Excellent

1-2

X

®

S

f

to 287°

15-25

28

4

775-796

Moderate to Excellent

<l-2

A

121°-301°

15-22.5

29

4

814-846

Moderate to Good

1-4

Xi

X

®

®

S

to 278°

10-25

1.25-2.0

30

4

872-920

Good to Excellent

<l-2

*l

S

175°-355°

25-30

31

5

979-004

Moderate to Excellent

<l-2

Xi

32

5

049-085

Good to Excellent

<l-2

Xi

33

5

133-168

Poor to Excellent

<l->4

X

34

5

270-286

Excellent

<l-2

Xi

35

6

401

Poor

>4

X

36

6

460-485

Moderate to Excellent

<l-4

Xi

37

6

544-578

Moderate to Excellent

<l-2

Xi

A

to 283°

10-15

<2.0

A : 002°-182°

37A

6

628-670

Poor to Excellent

<l-2

Xi

H : to 350°

38

6

747-766

Good to Excellent

<l-2

X

39

6

837-846
(color)

Good

1-2

X

40

7

965-966
(color)

Poor

<1

X

41

7

134-164
(color)

Moderate to Good

<l-2

Xi

A(?)

010°-190°

10-12.5

1.-1.25

42

7

254-282
(color)

Moderate to Good

<l-2

X

S

015»-195°

12.5-15

43

7

383-421

Good to Excellent

<l-4

® 1

X

X

A

to 325°

10-20

1.5-3.0

44

8

564-587

Moderate to Good

1-2

X

A

to 030°

15-25

45

8

692-715

Moderate

<l-4

Xi

46

8

843-858

Moderate

1-2

y

47

8

988-003

Moderate to Good

1-2

X

00

S

110°-290°

15-20

A : to 285°

48

9

102-116

Poor to Good

<l-2

X'

X

®

S

125°-305°

10-15

1.25-2.5

49

9

185-200

Moderate to Good

1-2

Xi

X

®

A

to 184°

20-25

2.0-3.0

50

9

312-336

Moderate to Excellent

<l-2

X

fc

A

®

to 197°

10-15

1.25-2.60

51

9

473-501

Moderate to Excellent

<l-2

to 240°

52

10

707-724

Moderate to Excellent

<l-2

Xi

1

S

A

053°-233°

10-20

A: 035°-215°

53

10

815-845

Moderate to Good

<l-2

S

076°-255°

10-20

54

10

952-972

Moderate to Excellent

<l-2

X'

®

S

075°-255°

15-20

94

rine canyon area (Cruise RoS2).

Organisms

Lebensspuren
P = Present
C = Common
A =: Abundant

Shell

(Mainly

pelecypod

Relative

percent

Coelenterates

Echinoderms

Polychaete

Worms

and
Related
Forms

Crustaceans

Fish

Remarks

A

A

P
P
P

3-12 1

5-12
2-5

7-20
3-12

1-7

p

1-7

p

1

7-15

3-5

0-3

p

1

15-30

p

5-10

p

p

p

1-2

3

A

A

P

3-11

A

A

P

2-3

P

1-3

A

1-3

P

1-5

C

A

2-5

A

A

A

A

A

A

A

A

( ?:

(?)

x

< ?)2

(?)

(?)

tubes •■
tubes

tubes

tubes

tubes

tubes

tubes
tubes

tubes

worm ( ?)
\vorm( ?)

tubes
tubes
worm ( ? )

tubes
tubes
tubes

1 Large shells mainly concave up.
1 All photos too poor to interpret
(camera too far off bottom).

1 Beginning of station.

2 End of station.

1 Straight ripples probably young-
er than interference ripples.

1 Beginning of station, straight

ripples dominant.

2 Middle of station, sinuous rip-

ples dominant.
;i End of station, sinuous and in-
terference ripples.

1 Beginning of station.

2 End of station.

3 Not oriented.

1 In one photo only.

1 Murky nature of photos suggest
material in suspension.

1 Large boulders observed (to > 60
cm in diameter).

1 Maximum diameter 25 cm.

2 NE-SW alignment of shell con-

centrations in ripple troughs.
1 Maximum diameter 30 cm. ;
gravel rare in later frames.

1 Maximum diameter 2-3 cm.
1 Granular nature may be due to
faecal pellets or mud clasts.

i Ibid.

2 Current direction obtained from
scour lineation.

1 Granular texture may be due to
faecal pellets or mud clasts.

1 Maximum diameter 20 cms.

1 Granular texture may be due to

faecal pellets or mud clasts.
i Ibid.
1 Ibid.

1 Ibid.

i Ibid.
1 Ibid.
1 Ibid.

1 Clay appears stiff.

1 Large fractured rock ledge (see

Plate 27 A) and numerous
angular blocks of rock at least
20 cm thick.

2 Ping-pong ball-like echinoid.

1 Granular texture may be due to

faecal pellets or mud clasts.
1 Possible crinoid.

1 Maximum diameter 40 cms.

Possible sponge observed.
1 Maximum diameter at least 1
meter.

1 Granular texture may be due to
faecal pellets or mud clasts.

1 Maximum diameter 7.5 cm (may
be an unidentified organism).

1 Maximum diameter 20 cm.

# U.S. GOVERNMENT PRINTING OFFICE: 1969 O-33O-307

95