Sedimentry Structure

Question 1

What is stratification (bedding) in sedimentary rocks?

Answer 1

Layers of sediment varying in composition or grain size.

Question 2

What is cross-bedding and what does it indicate?

Answer 2

Inclined layers formed by wind or water currents; indicates flow direction.

Question 3

What is graded bedding?

Answer 3

Layers showing a change in grain size from coarse at the bottom to fine at the top, often from turbidity currents.

Question 4

What are ripple marks?

Answer 4

Small ridges formed on sediment surfaces by water or wind.

Question 5

What causes mud cracks in sedimentary rocks?

Answer 5

Polygonal cracks formed by drying mud in arid or tidal environments.

Question 6

What are fossil tracks and burrows?

Answer 6

Trace fossils recording the activity of organisms.

Question 7

What characterizes fluvial depositional environments?

Answer 7

Rivers and streams; channel sands, point bars, floodplain muds.

Question 8

Where do deltaic sediments form?

Answer 8

Where rivers enter oceans or lakes; mix of freshwater and marine sediments.

Question 9

What type of sediments are typical in lacustrine environments?

Answer 9

Fine sediments like clays and silts, often with varves (annual layers).

Question 10

What sediments are found in marine environments?

Answer 10

Sands, silts, clays, and biogenic materials on continental shelves, slopes, and deep ocean basins.

Question 11

What is an aeolian environment?

Answer 11

Wind-blown sediments, such as desert dunes.

Question 12

What characterizes glacial depositional environments?

Answer 12

Sediments deposited by glaciers, often unsorted till or stratified outwash.