DO NOW Pick up notes and lab. Turn in Review #29.

REVIEW #28 How are weathering and erosion related?

REVIEW #28 TYPES OF WIND EROSION ___________________- The largest particles which are too heavy to be lifted into the air are rolled along the surface. __________________________ - larger particles are pushed and bounced along the ground. This accounts for the most wind transport of sand. ___________________________- small particles become airborne for long distances.

REVIEW #28 Which of the above types of wind erosion was responsible for the dust storms of the Dust Bowl?  What were two causes of the Dust Bowl during the 1930s?

REVIEW What size particles settled first? Last? Why? SAND CLAY SAND is bigger and heavier. CLAY is lighter

LAB: SORTING AND SEDIMENTATION The settling rate depends on particle size, shape and density as well as on the velocity of the river.

LAB: SORTING AND SEDIMENTATION Turbidity: the cloudiness or haziness of a fluid caused by large numbers of particles as water settles. As the velocity increases, both the size of particles in suspension increases and the amount of material in suspension increases (faster moving water holds more and bigger sediment).

LAB: SORTING AND SEDIMENTATION Purpose: To explore turbidity and observe the way particles are sorted during deposition

LAB: SORTING AND SEDIMENTATION Materials: Clear jar, filled 1/3 full with sediment and filled to the brim with water Paper clip - bent as illustrated below with bead on end Pencil Metric ruler

LAB: SORTING AND SEDIMENTATION NOTE: We will begin this lab BEFORE starting the Presentation and stop to collect data every five minutes Procedures: (see diagram) 1. With lid on tightly, shake jar vigorously. 2. Quickly set jar down and open lid.

LAB: SORTING AND SEDIMENTATION 3. Make observations as follows (two people are needed): One person lowers a paper clip into water to level where it disappears from view as observed from the top and holds it there. The paper clip must be lowered next to the edge of the jar so it can be seen through the glass. The other person measures the depth beneath the water surface in MILLIMETERS at which the paper clip disappears from view as observed from the top. Record the observation in the Data Table below. Repeat every five minutes for 25 minutes.

LAB: SORTING AND SEDIMENTATION

LAB: SORTING AND SEDIMENTATION Go collect first data point and return to your seat.

RIVERS AND LANDSCAPE EVOLUTION

STREAMS FLOW INTO RIVERS Channel - narrow depressions that streams follow as they flow downhill. Tributaries – smaller streams or rivers that feed into a larger one.

PARTS OF A RIVER Source – where it begins. Meanders – winding pattern of curves in a river. Floodplains – valley floor around rivers that flood.

PARTS OF A RIVER Levees – sediment deposits along banks of a river. Mouth - part of a river where it flows into the sea, river, lake, reservoir or ocean.

River Deltas A DELTA is where stream empties into large body of water. Decrease in velocity (speed). Load (sediment it is carrying) deposited. Triangular shaped. Formed slowly over time from erosion and deposition.

River Deltas

Alluvial Fans Alluvial Fan forms where streams descend steep slopes onto a flat plain. Often formed with temporary streams. Made up of deposits of load.

Alluvial Fan VERSUS DELTA A delta forms in water and an alluvial fan forms on land. DELTA ALLUVIAL FAN

RIVER EROSION Water moves faster on the inside of outside curves – increases erosion. Water moves slower on inside curves – greater deposition.

RIVERS CHANGE OVER TIME Over time, rivers become wider and deeper. Stages: Youth Early mature Mature Old Age EARLY EARLY MATURE MATURE OLD AGE

OXBOW Lakes The wide curves of meanders cause the formation of oxbow lakes. Differences in speed: Outside curve – faster speed – erosion. Inside curve– slower speed – deposition.

Lakes Begin to form when water collects in a depression. Most are: Short-lived in geologic terms (temporary). At high latitudes. Form from precipitation and melting ice/snow.

Sedimentation and Sorting Rivers deposit sediment along banks and in lakes. As water slows down, the largest particles (sediment) are dropped first. Sorting is process by which particles having a particular size or characteristic are concentrated.

Sedimentation and Sorting

ROCKS FROM DEPOSITION AND SEDIMENTATION Rock eventually forms based on sediment, providing clues to past environments: Conglomerate – rounded (river) stones Breccia – angular fragments Sandstone – sand Shale – silt and/or clay

Review What sequence do the pictures belong in according to the order in which they occurred? D B C A

LAB: SORTING AND SEDIMENTATION Analysis: Summarize your observation of how the rate of change in turbidity changes with time after shaking. What is the relation of grain size to settling rate? How does turbidity of a river change with water flow? How long would it take for the paper clip to be visible on the surface of the sediment? 

LAB: SORTING AND SEDIMENTATION

TO DO Finish lab and turn in tomorrow.