1. LAB 4 Beach Profiles and Sediment Characteristics
Coastlines: Beach zones
Sediment characteristics, hard stabilization
Quantification using sieves, scales, and graphical representation of results

2. Introduction
This lab examines sediments in one environment, the beach, which is the important interface between land and sea
The beach is only one of many different environments in which sediments are deposited
The beach is part of a coastline.
These slides try to give some perspective as well as more background on the particular barrier beach environment.

3. Coastlines
Coasts classified as being erosional or depositional (i.e., lose or gain sediment)
Most eastern USA (passive, trailing) coasts are depositional
Includes the Gulf coast of Texas
Most western USA (active, collision) coasts are erosional (California)

4. Beach dynamics Dynamic processes maintain and destroy the beach
Summer waves deposit, winter waves erode
Waves in surf zone produce currents, particles suspended - moved on or offshore
Waves crest approaching coast at angle promote a longshore current (drift)
Because of this, West and East coasts of USA sediments are slowly moving southwards

5. Summer vs Winter Profiles5

6. Sediment classification
Texture
Size, sorting, roundness
Composition
Neritic- coastal sediments
Coarser sands and muds
Pelagic sediments - open ocean
Fine-grained clays and biogenic oozes
Origin
Terrigenous (land)
Biogenous (living organisms)
Hydrogenous (water)
Cosmogenous (space origin)
Poorly sorted
Well sorted
One size dominates
Wide variety of size ranges in ~ equal amounts
Sediments are classified in a variety of ways, by texture, composition and origin

7. Padre Island beach shells – describe the sediment characteristics and classify these particles based on texture, composition and possible origin.
Well sorted or poorly sorted??

8. Central Padre Island – how does this sand compare to the Padre beach shells?
Well sorted or poorly sorted??
Little dune vegetation
Wind blown sand over island

9. Hard Stabilization
Man-made objects such as groins, jetties, seawalls, and breakwaters affect sediment movement.
Look at pictures of hard stabilization and determine the resulting changes to the beach/shoreline.

10. 10

13. 13

14. Seasonal beach profiles
Notice the difference in winter and summer/spring beach profiles
Compare this to the chart you produce from Table 4 in today’s lab.

15. Beaches: A River of Sand - Video

16. Class Exercise Compare beach environments
Sediments you will examine today through visual examination and separating and sorting techniques:
Texas coastal samples
Malaquite Beach – northern Padre Island area
Little Shell – 30 km down Padre Island
California coastal sample
Huntington Beach
Compare beach zones using data from two Texas beach samples:
Malaquite Beach
Little Shell Beach
Hard stabilization- observe the effects of man-made objects on the beach and shoreline
Observe seasonal effects on beach systems

17. Dry sieving technique Used to sort and separate particles by size
Standard Sieve #
Screen Mesh Size
Descriptive Name
Numeric (mm)
Log2 (mm) 5 4 22
fine gravel, shell fragments 10 2 21
very fine gravel, granules 18 1 20
very coarse sand 35
0.5
2-1
coarse sand 60
0.25
2-2
medium sand
120
0.125
2-3
fine sand
230
0.063
2-4
very fine sand
Mud Particle Sizes
0.0039
2-5
silt
<0.004
2-8
clay

18. Dry sieving technique Used to sort and separate particles by size
Large mesh
openings
Small mesh

19. Picture of jetties for exercise 4.3 question 4