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8.3.1.3: Salmon Creek Beach - Geosciences

8.3.1.3: Salmon Creek Beach - Geosciences


Welcome to Salmon Creek Beach located in beautiful Sonoma County, California! This site was visited, along with several others in Bodega Bay, on January 31, 2015 in order to observe active sedimentary processes and to document spacial trends in sediments within an environmental context. Salmon Creek Beach consists of an estuary that is fed by Salmon creek that originates from the surrounding coastal hills and empties into the Pacific Ocean. Depending on the time of the year and the meteorological conditions, the estuary may or may not fully reach the ocean; however, on the day the site was visited, the Pacific Ocean and Salmon creek were connected. Looking at the left, southern side of the above image, the back of the estuary is lined with dunes and is a very low-energy environment where flow velocities are very low. In the images below, we see an increase in energy and flow velocity as water moves through a smaller, narrower area and bends around to where it meets with the Pacific Ocean. We can also see the cut bank of where the channel water level used to be at higher tides as it meanders on the beach toward the ocean. The most prominent sedimentary structures that were observed at Salmon Creek Beach were current ripples, antidunes, dunes, and wind ripples, along with the bioturbation (human and wildlife footprints).

The first observed sedimentary structures were current ripples. These type of ripples indicate present unidirectional flow moment, which was initially determined to be north and then west closer to the bed of the ocean. The direction of the ripples changed where the flows of Salmon creek and the Pacific Ocean began to meet. The flow direction can be concluded by the direction of the Lee side, or grain attachment point. This side is where the grains being transported go from being suspended in the flow to depositing "down" to the bed again. The process of lamination is where such grains begin to repeat the process and produce wavy surface features known as ripples. The ripples seen at the beginning of Salmon creek, bottom images,were in between sinuous and linear and were measured to have a wavelength (from crest to crest) of 30mm with a flow direction going north. This small wavelength was suggestive of calm flow speeds, allowing fine sediment to be deposited.

(penny for scale) (footprint for scale)

Sample SC-01 was collected here and was later analyzed. The sample contains well-sorted very fine to fine sand consisting of quartz, lithics, and occasional pieces of glass and shells. The sediments here overall are well-rounded to rounded and spheroidal which suggests the grains are texturally and compositionally mature, meaning they are far away from the source of sediments.

(Sample SC-01)

Closer to the ocean as the channel meanders, ripples are still observed however they change in magnitude and direction. Given the flow is directed towards the ocean, the ripples change to that direction (west), bottom left. As the channel nears the ocean, ripple wavelengths were observed to get longer and sand grains became coarser. Wavelengths were now measured to be up to 90mm, consisting of the same sediments. These sediments were coarser and didn't share the uniform spherocity of the grains up the creek. The reason for this change in ripple characteristics was a result of flow differences. The flow had increased here and was able to carry more coarse sediments. The changes in flow allowed for the formation of reactivation surfaces, bottom right.

Reactivation surfaces occur from bidirectional flow where a one flow direction dominates and creates the ripple structure while an opposing weaker flow erodes the top of the ripple.

Aside from the current ripples observed, an area by the bend of the channel had interference ripples. Unlike the unidirectional ripples formed by current flow, these ripples indicate bidirectional flow. This means that at some point in tide fluctuations there were two different flow directions. These directions were from the creek to the ocean and from the ocean to the creek, or east to west. Indicative features of interference ripples are visible in the picture below, where sinuous ripples cross one another.

(penny for scale)

Along the stream connecting the lagoon and the ocean was observable a sedimentary bedform recognized as antidunes. These formations are possible when Froude’s number of a flow is close to one so standing waves may form on the surface of the water before steepening and breaking in an upstream direction. As a result, the sand on the bed develops a bedform surface parallel to the standing wave; therefore, as the flow steepens, sediment accumulates on the upstream side of the bedform creating these unique structures. In the video recorded at Salmon Creek, we find that the fluvial environment present has the flow velocity needed to form the antidunes.

Video taken at Salmon Creek Beach showing the antidunes that formed in the shallow stream with a high flow rate.

Further down from where the antidunes were seen where the channel meets the swash zone, Sample SC-02 was taken. Sample SC-02 was analyzed to be coarser than SC-01 and consisted of well-sorted fine to medium sands primarily composed of quartz and lithics. Sediments in the swash zone are exposed to medium energy processes which gives us the medium sized grains as opposed to those finer grains found in the breaker and surf zone. The main sedimentary structures associated with Sample SC-02 would be bioturbation and faint lines of longshore drift.

Sample SC-03 was collected about halfway towards the dunes (going east) from the swash zone of the ocean past the antidunes. (See pictures at top of page for exact location). This sample contains moderately-sorted very fine sand to granule-sized grains that are composed of quartz, lithics, and shells. In this area, bioturbation as well as ripples were observed in the area. Coarser grains were concentrated on top of finer grains.

Other sedimentary structures present were dunes and wind ripples. Dunes, also recognized as “megaripples,” are bedforms distinctly larger than ripples. These bedforms are usually known as hills of sand that are produced by either water flow or wind. Dunes vary in size and are formed as sediments are pushed up the stoss side and are deposited on the lee side. At Salmon Creek Beach, we find that the dunes are primarily shaped by wind activity and are primarily comprised of the very fine-grained sediments transported and deposited by wind. These Aeolian dunesraneg from about 3 meters to 600 meters in wavelength and are between 10 cm and 100 meters high. Again, the migration of sediments, saltation, up the stoss side to the crest form structures like Aeolian ripples.

Aeolian Ripples are formed as grains migrate across a bed of sand creating patches of piled up grains. These “piles” of grains are due to irregularities on the surface of the sand that then pile in a perpendicular fashion equally spaced apart; therefore, the crests formed produce these aeolian ripples comprised of very fine to medium sized grains. The direction of these ripples are dependent on the direction of the wind which carries different sized grains depending on the strength of the blowing wind. The coarser grains in any given wind current are concentrated on the crests where the finer grains continue being transported by the wind. As the crests develop, the grains avalanche down the lee side into the rough forming cross-laminations.

In the figure above, we can notice the aeolian ripples formed by the wind blowing in the southward direction. Each ripple is equally spaced out and is comprised, more or less, of the same fine sized grains.

Sample SC-04 was collected in this area and is consisted of well-sorted medium to very-fine quartz and lithic sands. The sedimentary structures associated with this sample are bioturbation (human and animal footprints), wind ripples, and dunes.

This coastal location has experienced an immense amount of sediment allocation from different sources. Methods including air and water have deposited the sediments seen today. The most dominant sediment redistributing source is water, carrying sediments during tidal fluctuations. At low tide, which was observed the day of the trip, all of the sedimentary structures described were able to be seen. At high tide, some structures would have been destroyed or altered due to water movement. With tides comes wind, which can also transport sediment. Both dunes and ripples at Salmon creek were created and sediment was transported out of the area to Bayside Park and further south as a result of these transport mechanisms.

Ripples: https://www.youtube.com/watch?v=VAcr...ature=youtu.be​

Preface- Ripples were present at Salmon Creek and Bayside Park. Of course, they differ in some ways but are also similar. At both sites one is able to see grain size, composition, and angularity extremely up close. Both stops were at low tide which allowed for this. Given they have water flow fluctuations, one is able to see these ripples. Salmon Creek, however, had a slightly higher energy level than Bayside Park. At the creek ripples can be seen above and below a water surface. At Bayside Park, only ripples above a water surface are visible. This lead to the conclusion that although ripples are formed at both sides, different flow conditions influence their form and location on the bed.

  • Marcelle d'Almeida
  • Rebeca Ontiveros
  • Robert Torres
  1. Sedimentology and Stratigraphy 2nd Edition, Gary Nichols, 2009. Print

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8.3.1.3: Salmon Creek Beach - Geosciences

Notes on significant weather not yet written

Significant rainfall, strong winds, strong wind gusts and abnormally high and low temperatures for this day are given below. Descriptions of significant weather events are added here when time permits and reliable information is available. This is sometimes well after the event!

National weather extremes for today

Records set this day (previous record and years of computerised record shown in brackets):
Highest daily rainfall for any month
Northern Territory:
014932 TINDAL RAAF 116.2 (107.7, 11)
Highest daily rainfall for March
Northern Territory:
014507 ALYANGULA POLICE 191.6 (133.8, 27)
014932 TINDAL RAAF 116.2 (72.2, 11)
Highest daily maximum temperature for March
South Australia:
018106 NULLARBOR 43.0 (42.0, 17)

Quality control note: Data is final. It includes late-received rainfall data and has been subject to BoM quality control checks.
Data is as received at 22:17EST, 27/10/2004.

Hottest Highest maximum temperature>Greatest variation above normal maximum Highest minimum temperatureGreatest variation above normal minimum

43.0 NULLARBOR W Agricultural SA
42.3 KYANCUTTA W Agricultural SA
42.2 CEDUNA AMO W Agricultural SA
41.6 MARREE NE Pastoral SA
41.6 PORT AUGUSTA AERO W Agricultural SA

+17.0 37.6 CAPE NORTHUMBERLAND Lower SE SA
+16.8 40.7 ELLISTON W Agricultural SA
+16.4 43.0 NULLARBOR W Agricultural SA
+15.6 42.2 CEDUNA AMO W Agricultural SA
+14.2 40.0 PRICE Yorke Pen/Kanga Is SA
+14.2 40.2 ADELAIDE (KENT TOWN) Adelaide/Lofty SA

30.0 NORTHERN ENDEAVOUR Islands ISL
28.0 MCCLUER ISLAND N Rivers NT
28.0 WULUNGURRU N Plateau NT
27.6 KURI BAY N Kimberley WA
27.5 OODNADATTA AIRPORT NE Pastoral SA

+10.2 24.5 MAITLAND Yorke Pen/Kanga Is SA
+9.0 26.8 MARLA POLICE STATION NW Pastoral SA
+8.3 27.5 OODNADATTA AIRPORT NE Pastoral SA
+8.3 23.0 STREAKY BAY W Agricultural SA
+7.6 22.2 CLEVE W Agricultural SA
+7.6 23.5 PORT PIRIE BHAS Lower North SA

16.6 NULLO MOUNTAIN AWS C Tablelands N NSW
17.0 DORRIGO (OLD CORAMBA RD) MidNorth Coast N NSW
17.2 KATOOMBA (NARROW NECK RD) C Tablelands S NSW
17.3 SALMON GUMS RES.STN. Goldfields WA
17.5 ESPERANCE AERO Lower West WA

-9.9 17.3 SALMON GUMS RES.STN. Goldfields WA
-9.2 19.5 NORSEMAN Goldfields WA
-8.6 22.0 SOUTHERN CROSS Goldfields WA
-7.8 25.0 PAYNES FIND E Gascoyne WA
-7.3 30.4 MARDIE W Pilbara WA

-0.7 LAKE ST CLAIR NATIONAL PARK Central Plateau TAS
0.9 CHARLOTTE PASS (KOSCIUSKO CHALET) Snowy Mtns NSW
1.2 LIAWENEE Central Plateau TAS
2.5 PERISHER VALLEY SKI CENTRE Snowy Mtns NSW
3.0 THREDBO VILLAGE Snowy Mtns NSW

-7.0 5.5 CRANBOURNE BOTANIC GARDENS E Central VIC
-6.6 5.0 JARRAHWOOD Lower West WA
-5.2 5.5 BRIDGETOWN COMPARISON Lower West WA
-5.2 7.6 DONNYBROOK Lower West WA
-5.2 4.7 STRAHAN AERODROME W Coast TAS

192.0 DEERAL N Coast--Barron QLD
182.6 LOW ISLES LIGHTHOUSE N Coast--Barron QLD
174.0 HAMERSLEY W Pilbara WA
167.0 GRAHAM RANGE N Coast--Barron QLD
161.0 BABINDA POST OFFICE N Coast--Barron QLD

WESTERN AUSTRALIA
W Pilbara
174.0 HAMERSLEY
142.4 TOM PRICE
125.5 DAMPIER SALT
65.0 CHEELA PLAINS
62.4 WITTENOOM
55.8 MILLSTREAM
52.6 MULGA DOWNS
E Gascoyne
124.6 PARABURDOO AERO
62.6 MININER
56.6 TANGADEE
56.0 MURCHISON DOWNS
Central West
98.0 WANARRA

NORTHERN TERRITORY
N Rivers
134.6 CUTTA CUTTA
125.8 DUM IN MIRRIE AWS
117.4 NITMILUK RANGERS
116.2 TINDAL RAAF
111.6 UPPER SEVENTEEN MILE CREEK
109.6 CHANNEL POINT
104.2 TANDANGLE HILL
103.8 NITMILUK RIDGE
100.0 DUM IN MIRRIE
82.6 MARANBOY HILL
78.0 LEADERS CREEK
78.0 LARRAKEYAH
74.8 KATHERINE AVIATION MUSEUM
74.0 BESWICK
74.0 SHOAL BAY
73.0 PORT KEATS AERO
71.0 FORT HILL WHARF
70.0 LEANYER
69.2 KARAMA
66.8 KATHERINE RESEARCH FARM
65.2 YEURALBA RIDGE
62.0 MARLOW'S LAGOON
61.4 FLORINA
61.0 RANKIN POINT
58.6 KATHERINE COUNCIL
56.0 WEST WATERHOUSE
53.0 THORAK CEMETERY
50.0 BERRIMAH RESEARCH FARM

QUEENSLAND
N Peninsula
53.0 PICCANINNY PLAINS STATION
S Peninsula
68.0 MUSGRAVE
N Coast--Barron
192.0 DEERAL
182.6 LOW ISLES LIGHTHOUSE
167.0 GRAHAM RANGE
161.0 BABINDA POST OFFICE
159.0 HAPPY VALLEY
154.5 BABINDA SUGAR MILL
150.0 WHYANBEEL VALLEY
145.0 DAINTREE TEA
144.0 MT SOPHIA
133.0 TREE HOUSE CREEK
130.0 BELLENDEN KER BOTTOM STN
129.0 CAIRNS SEVERIN ST
120.0 TOPAZ ALERT
119.0 MOSSMAN CENTRAL MILL
118.0 TOPAZ TOWALLA RD
104.2 CAPE TRIBULATION STORE
100.2 CAIRNS AERO
98.0 TAMARIND GDNS RENNEL CL
97.2 MOSSMAN SOUTH ALCHERA DRIVE
96.0 DAINTREE VILLAGE
96.0 COPPERLODE DAM ALERT
95.0 KURANDA HILLTOP
93.0 KURANDA RAILWAY STATION
89.0 MERINGA SUGAR EXP STN
87.0 BARTLE VIEW ALERT
80.5 MULGRAVE MILL
77.0 PORT DOUGLAS - FOUR MILE BEACH
73.0 SUTTIES CREEK ALERT
64.0 MILLAA MILLAA ALERT
62.0 GREENHAVEN ALERT
60.4 MALANDA POST OFFICE
58.0 MALANDA ALERT
53.0 CHILVERTON
50.0 YUNGABURRA POST OFFICE
N Coast--Herbert
123.0 RUSSELL RIVER
114.0 SOUTH JOHNSTONE EXP STN
114.0 TUNG OIL ALERT
109.0 MARCO STREET ALERT
103.0 TUNG OIL TM
97.0 CENTRAL MILL TM
84.0 NERADA ALERT
80.0 CORSIS ALERT
74.0 CRAWFORDS LOOKOUT ALERT
72.0 JARRA CREEK TM
65.0 MENAVALE ALERT
64.6 JAPOONVALE WARRAKIN RD
63.0 DARADGEE
58.0 EL ARISH POST OFFICE
51.0 ABERGOWRIE ALERT
Wide Bay/Burnett
52.0 BARGARA POST OFFICE
Darling Downs E
81.4 MOYOLA

QUEENSLAND
N Coast--Barron
LOW ISLES LIGHTHOUSE : 82(150/ 63 ) at 18:35
GREEN ISLAND : 78(130/ 65 ) at 09:29
Central Coast E
HAMILTON ISLAND AIRPORT : 91(130/ 63 ) at 20:08
Wide Bay/Burnett
HERON ISLAND RES STN : 80(140/ 63 ) at 17:51
RUNDLE ISLAND : 91(140/ 82 ) at 16:48
Brisbane/SE Coast
CAPE MORETON LIGHTHOUSE : 93(140/ 70 ) at 09:03
DOUBLE ISLAND POINT LIGHTHOUSE : 82(150/ 69 ) at 15:00
ISLANDS
Islands
WILLIS ISLAND : 76(100/ 67 ) at 14:59


Acknowledgments

We are very grateful to Katee Neesmith, Stephanie James, Kathy Davenport, Jon Delph, Katie Garman, and Madeline Job for their strenuous efforts during the IDOR Passive Seismic Project field work. We are very grateful to George Slad, Noel Barstow, and Pnina Miller of Incorporated Research Institutions for Seismology (IRIS) PASSCAL for their 24/7 field support far above and beyond the call of duty. Basil Tikoff, Jeff Vervoort, Richard Gaschnig, Annia Fayon, Mark Panning, Reed Lewis, and Mark Fernes provided crucial instruction through helpful discussions of geology, geochronology, and geochemistry and tectonics of the study area and of seismic techniques. The IDOR passive seismic project would not have been possible without the help and support of the people of Idaho and eastern Oregon, who cheerfully gave us permission to site and access seismic stations on their properties for 2+ years. We are grateful to Elaine Alexander and her colleagues at the U.S. Forest Service and to David Wolff and Tim Vanek of the Bureau of Land Management for their help in permitting. This work is supported by U.S. National Science Foundation grant EAR-0844187. We created all the maps and figures using the Generic Mapping Tools [Wessel and Smith, 1998 ]. Data analysis was performed using SAC (Seismic Analysis Code) [Goldstein et al., 2003 Goldstein and Snoke, 2005 ]. The seismic instruments were provided by IRIS through PASSCAL Instrument Center at New Mexico Tech. The seismic data used in this paper are freely available through the IRIS Data Management Center. The facilities of the IRIS Consortium are supported by the National Science Foundation under Cooperative Agreement EAR-1261681.

Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.


Watch the video: BeachDune interaction and the response of sandy beach and dune systems to relative sea level rise