How Roman harbors have stood the test of time
paragraph 1,The circular harbor at Caesarea, which sits on the coast of Israel, was constructed in less than 10 years, from roughly 23 to 15 B.C., on the order of King Herod, ruler of the Roman province of Judaea. The site chosen was an unobstructed length of coastline with no natural geographic features to break the waves rolling into shore or protect ships. The port's construction was nothing short of a Roman engineering marvel, comparable to the Colosseum or the aqueducts.
paragraph 2,Much of the vast structure, which includes two breakwaters,,superscript,1,baseline, three underwater piers that once held large statues, and a 60-foot-wide entrance for ships, stands today. The scholar Josephus' description, written nearly 2,000 years ago, still rings true: "Herod contended with the difficulties so well that the sea could not overcome the solidity of the construction."
paragraph 3,The trick to Caesarea's longevity was the concrete used to build the harbor. For more than a decade, John Oleson, a classical archaeologist at the University of Victoria, in British Columbia, has pursued the secrets of Roman harbors and their impressive durability. "People have been studying Roman concrete for 500 or 600 years, but they haven't done much with the concrete in the sea because it's more difficult to access. Also, until recently, people thought it was not as important as what you find on land," says Oleson.
paragraph 4,As head of the Roman Maritime Concrete Study (or ROMACONS), Oleson, along with University of Colorado Boulder maritime archaeologist Bob Hohlfelder and British architect Chris Brandon, examined samples from several ancient Roman ports. They found that there was, in fact, a key ingredient that made the material uniquely suited to hold up to the underwater environment.
paragraph 5,The Romans started building with concrete regularly beginning in the third century B.C., but the earliest uses go back roughly a thousand years further, to ancient Greece. Concrete is made of chunks of rubble held together by mortar. Today, mortar is typically made by mixing gravel, sand, and binders such as lime,superscript,2,baseline, and cement. According to Marie Jackson, a research engineer at the University of California, Berkeley, and ROMACONS collaborator, modern concrete begins to break apart underwater. The material used by the Romans for maritime construction, however, actually gets stronger over time.
paragraph 6,In the first century B.C., the architect and engineer Vitruvius wrote an expansive work on Roman building methods called ,begin italics,De Architectura,end italics,. In it, he describes a substance found near Baia, a resort town on the Bay of Naples, and around Mount Vesuvius, that "when mixed with lime and rubble, not only lends strength to buildings of other kinds, but even when piers of it are constructed in the sea, they set hard under water."
paragraph 7,The ROMACONS team set out to confirm what Vitruvius had written by studying the concrete used to build harbors dotting the Mediterranean, including Caesarea, Portus (one of Rome's great harbors), Pompeiopolis in modern-day Turkey, and Hersonissos in northern Crete. The researchers took cores, measuring four inches in diameter and up to 20 feet long, from various parts of each harbor, many of which are now submerged.
paragraph 8,Jackson was then enlisted to investigate the concrete's physical characteristics and material makeup. She found that its compressive strength, meaning the weight it can bear, was much lower than that of modern concrete, so it wasn't suitable for tall aboveground architecture. When she compared the trace elemental composition of the mortars in the cores, however, she confirmed Vitruvius' assertion. All the samples contained volcanic ash that came either from Mount Vesuvius or Campi Flegrei, volcanoes located east and west of Naples, respectively. The same ash was also found in a sample sent to the team from Quarteira on the coast of southern Portugal.
paragraph 9,The specific type of ash is known as pozzolana after Pozzuoli, the town near Campi Flegrei where it was originally used, but Oleson says you can find it throughout the Bay of Naples. "If you're rowing a boat along the coast near Baia, parts of the coastline are made up of this pozzolana," he explains.
paragraph 10,Jackson credits the Romans with noticing that, over time, the ash consolidated into a volcanic rock called tuff. With that insight they formulated their unique mortar recipe: pozzolana, lime, and seawater. That mixture, which she says must have been arrived at by careful experimentation, results in the growth of a durable binding substance throughout the concrete mixture. "Pliny the Elder says that they needed something that lasts a long time and gets stronger with age." Jackson explains, quoting the ancient Roman scholar and natural historian (who himself died from the eruption of Vesuvius that buried Pompeii in A.D. 79). Because seawater is part of the reaction, placing this mortar in the Mediterranean promotes greater adhesion rather than causing the concrete to crack.
paragraph 11,According to Oleson, the Romans relied on the pozzolana for maritime construction for two centuries, beginning about 40 B.C. He suggests that its presence in ports as far east as Caesarea and Alexandria shows that the ash was exported throughout the empire from the Bay of Naples.
paragraph 12,"ROMACONS has managed to document the evolution of this [maritime concrete] industry and the type of materials used, and to document the trade across the Mediterranean, a trade that previously was not known," Oleson explains. He posits that, for example, a grain ship arriving in Rome's Portus from Alexandria might have been sent back with pozzolana stored in sacks for ballast,,superscript,3,baseline, which would then be used in port construction back east.
paragraph 13,The reactivity of Bay of Naples pozzolana was well known in antiquity, says Lynne Lancaster, a classics professor at Ohio University. She has documented shorter-range trade within the Roman Empire in her research, including the export of light-weight volcanic rocks from Sardinia for use in building vaults in Carthage. What the ROMACONS project has identified, Lancaster says, "is a Mediterranean-wide trade that is being used to build the ports, which in turn is used to increase the trade. This contributes more to the economics and infrastructure of the Roman Empire." And in building those harbors that were so critical to the empire's success, it is clear that the Romans were extremely careful to choose a material that would ensure longevity—of both port and empire.
"Built to Last" by Nikhil Swaminathan. Reprinted with permission of ARCHAEOLOGY Magazine, Mar/Apr 2014. Vol 67, NO 2. www.archaeology.org (Copyright, The Archaeological Institute of America, 2014)
,begin bold,,superscript,1,baseline,breakwaters,end bold, offshore walls that protect a harbor from waves
,begin bold,,superscript,2,baseline,lime,end bold, powdered mineral containing calcium
,begin bold,,superscript,3,baseline,ballast,end bold, heavy cargo carried by a ship to help keep it stable
Question 1
This question has two parts. Answer Part A, and then answer Part B.
,begin emphasis,Part A,end emphasis,
How does paragraph 1 ,begin emphasis,best,end emphasis, contribute to the development of ideas in the passage?
Question 1 Answer options with 4 options
1.
It establishes the idea that the location of Caesarea was carefully selected.
2.
It emphasizes the regions most impacted by trade generated from Caesarea.
3.
It establishes the idea that the building of Caesarea was an incredible accomplishment.
4.
It emphasizes the astonishing amount of work that went into the construction of Caesarea.
Question 2
,begin emphasis,Part B,end emphasis,
Which detail from paragraph 1 ,begin emphasis,best,end emphasis, supports the correct answer from Part A?
Question 2 Answer options with 4 options
1.
"on the coast of Israel"
2.
"less than 10 years, from roughly 23 to 15 B.C."
3.
"or protect ships"
4.
"nothing short of a Roman engineering marvel"
Bot GPT 3.5
answered
3. It establishes the idea that the building of Caesarea was an incredible accomplishment.
For Part B, the detail that supports this answer is:
"nothing short of a Roman engineering marvel"
