Background:
The goal of the Deep Sea Drilling Project (DSDP) was to investigate the sediments and rocks beneath the deep oceans by
drilling and coring. The data featured in this exercise were taken from ocean sediment cores collected by the Glomar
Challenger drill ship, at seven sites east and west of a mid-ocean ridge, during DSDP Leg 3, in late 1968. The age of the
contact between the sediment and the basalt of the ocean floor was determined by identifying the nannofossils found at
each contact. (Note: The links in this paragraph are for your own research, and are not required readings necessary for
completing this assignment)
Questions for Exploration:
- In the paragraph above we learn that scientists were studying nannofossils (very small fossils) in sediment found
sitting on top of oceanic basaltic crust. These nannofossils were primarily coccolithophores and foraminfera, mixed
with small amounts of abyssal clay. Using this information, and your textbook readings, what specific type of
sediment were researchers analyzing at this location? - In the paragraph above, we also learn that scientists took cores (holes drilled into sediment and rock) at the contact
between sediment and basaltic oceanic crust. Which figure in your textbook, Chapter 4, best depicts what the
seafloor and sedimentation looks like in this location? - Familiarize yourself with the map showing
the DSDP Leg 3 drilling locations and the
position of the mid-ocean ridge (Figure 1 to
the right). Using the latitude and longitude
coordinates on the sides of the map, and this
online map for reference, in what ocean
were these samples collected?
EE1 Page 2 of 2 - The table to the right shows data
collected from the sites shown in
Figure 1. These data tell use the age of
the sediment at the sediment/crust
contact at each site. The sediment age
was determined by the fossils found in
the sediment; this is a paleontological
age. Using the data in Table 1 below,
write the age of the sediment at the
sediment/crust contact for each site
on the map in Figure 1. - Looking at the map and the ages you wrote on Figure 1, relative to the mid-ocean ridge, where are the youngest
samples? Where are the oldest samples? - This age relationship was the proof scientists needed to say that seafloor spreading does occur at mid-ocean ridges.
Explain why this relationship tells us seafloor spreading is occurring by relating processes of sediment deposition
to ridge movement. - If you could acquire data of a different type from these same sites to further provide proof, what other data might
be used to study seafloor spreading? Explain how this data would be useful.
Extra Credit Question
Using the data given in Table 1, calculate the rate of seafloor spreading of this mid-ocean ridge in km/m.y., then
convert your answer to cm/year. Rate is calculated as: Rate = Distance ÷ Time. You will have to convert kilometers to
centimeters, and millions of years to years (1 million years = 1,000,000 years).
Sample Solution
