Power Tools for Technical Communication: Headings Practice


In this lab, you compose and add headings to a technical document:
  1. Copy the text below this box, and paste it into your preferred word-processing software.

  2. Add second- and third-level headings at the appropriate points in the text and at the appropriate levels. Read carefully!

  3. You are welcome to use other fonts or other typographical effects, but bold on these headings works just fine.

  4. Put your name, Headings Practice: Print, and the date on this document, and show it to your instructor.


Scientists have found evidence that an era of frigid temperatures that occurred in much of North America and Europe from 1300 to 1850 were likely caused by a thermohaline circulation shutdown. No one believes that this little ice age was caused by humans releasing greenhouse gases into the atmosphere, but evidence suggests that certain natural climate cycles melted Arctic ice and ushered in this frigid period. In 1989, Lloyd Keigwin, senior scientist in the Woods Hole Geology and Geophysics Department, led an effort to collect core samples from a seafloor plateau called the Bermuda rise in the northern Sargasso Sea, approximately 200 miles northeast of Bermuda. These sediments contain tiny invertebrates called foraminifera that supply information about the temperature of the ocean in which they lived based on the thickness of their calcium carbonate shells. Using the foraminifera data and carbon dating, Keigwin uncovered data about drastic climate changes over the past 1,000 years. Keigwin speculated that because the Sargasso Sea was well mixed, the cooling must have been widespread, and he warned that the climate cycles are continuing "right up until today." Further evidence that a thermohaline shut-down can cause a cooler climate was discovered in the late 1960s when a huge pool of near-surface fresher water appeared off the east coast of Greenland. Oceanographers suspected that it formed as the result of a large ice discharge into the Atlantic in 1967. The drifting mass of water, known as the Great Salinity Anomaly, settled in the North Atlantic in the early 1970s where it interfered with the thermohaline circulation by stopping deepwater formation in the Labrador Sea. According to scientists who studied the anomaly, it shut the system down for a few years and caused some very cold winters, particularly in Europe. Because the formation was small, it was able to disperse in a relatively short period of time; however, scientists fear that the one accumulating in the North Atlantic today is too massive to disperse in even a few decades.


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