Ancient/Classical History

Grooves in a sandstone cliff reveal ancient tool sharpening

Anonymous — Wed, 21 Feb 2024 21:11:10 +0000

Grooves in a sandstone cliff reveal ancient tool sharpening Anonymous (not verified) Wed, 02/21/2024 - 14:11

Jeff Mitton

By rubbing a spear head against stone to form or sharpen it, a groove is gouged very similar to the grooves beside the Procession Panel

Comb Ridge is a monocline spanning between southeastern Utah and northeastern Arizona—a formation 80 miles long with a north-south orientation, rising gradually on the eastern side and dropping precipitously 600 feet on the western side. It is an immense and magnificent structure and it has truly ancient Native American history, including the discovery of an intact Clovis Point spearhead and a petroglyph of a mammoth—both of which date to 13,000 years ago.

In addition, it is home to Ancestral Puebloan dwellings that were occupied from 1150 to about 1290 AD. In 1990, teachers discovered a large petroglyph panel at Comb Ridge that is now called the Procession Panel. Near the Procession Panel, I found something that I did not understand.

At the top of the page: Comb Ridge during the later hours of the afternoon. Above: The Procession Panel depicts 179 people converging at a kiva, a space dedicated to rites and political meetings. Images by Jeff Mitton.

Monarch Cave is an Ancestral Puebloan dwelling in a large alcove at the end of a canyon, beside an intermittent waterfall and high above a splash pool. The structures have some intact walls, and the cooking area is littered with small corn cobs. Several metate depressions were formed in the floor by grinding corn with a small rock called a mano. The ceiling is darkened with the smoke of cooking fires and a nearby wall is stained with the activity of tanning leather.

The two approaches to the alcove are very narrow, so the site was easily defended. Monarch Cave was occupied from 1150 to 1290 AD, when most of the people in the Four Corners area abandoned their ancestral homeland due to drought and famine.

The Procession Panel, above Monarch Cave and farther west, decorates a vertical red rock wall that catches sunlight late in the day. It is 15 feet long, and it depicts 179 people coming from three directions to converge at a kiva, a meeting place with spiritual significance.

Monarch Cave is an Ancestral Puebloan dwelling on Comb Ridge. Image by Jeff Mitton.

Two of the people wear bird headdresses, and several others are carrying hooked staffs, indicating that they are chiefs. Animals include bighorn sheep, deer, snakes and either wolves or dogs also are depicted. Hunting activity is represented by atlatls (slings to hurl spears), and two animals depicted in the panel are impaled by spears.

When I was at the Procession Panel, I looked around for other petroglyphs. Approximately 70 feet north of the panel I found two vertical grooves in the rock. They were about one foot long, about three-eights inch wide and one-half inch deep and in cross section were V-shaped. They did not look like art, but they appeared to be purposely formed. I looked up, then down, but they did not point to anything unusual. I did not know what these were.

It turns out that many Native American sites have grooves gouged into rock. The Cape Cod National Seashore in Massachusetts has a display near Nauset Marsh of a 20-ton communal sharpening stone called Indian Rock. It commemorates thousands of years of activity of the Nauset people, who used the rock to sharpen spear points, harpoons and fishhooks.

Grooves in stone were formed by sharpening of weapons. Image by Jeff Mitton.

A similar display in Chatham, Massachusetts, recognizes the long history of the Monomoyick people with one of their sharpening stones. And for thousands of years, Native American people from at least 15 tribes in the northwest traveled to Kettle Falls on the Columbia River between Oregon and Washington to harvest salmon leaping up the falls.

All who came to catch fish were invited to sharpen their spear heads on the sharpening rock, a boulder weighing one ton that is now on display on the bank above the river, commemorating the times when the river ran free and Native American people lined its banks harvesting salmon. Here in Colorado, sharpening grooves are prominent at Balcony House in Mesa Verde National Park.

Archeologists have described and demonstrated the efficacy of abrasion for sharpening stone spear heads, bone awls or needles. By rubbing a spear head against stone to form or sharpen it, a groove is gouged very similar to the grooves beside the Procession Panel. Experiments with sharpening spear points produce grooves that are straight, V-shaped in cross section and shallower at the ends, like those at the Procession Panel.

However, Native American people used many implements, from large, heavy cutting tools wielded with two hands to butcher bison to axes for cutting trees to small knives for preparing food. For each of these, the shape of the groove differs because the shape and size of the tool differed. Sharpening grooves are seen at many Native American sites and on other continents.

Comb Ridge at sunset. Image by Jeff Mitton.

The Procession Panel shows atlatls, but not bows and arrows. The rock art panel was dated to 760 to 800 AD, about the time (800 AD) that bows and arrows replaced atlatls.

Once I began a literature search on grooves in stone at Native American sites, I was humbled by my realization that I had been ignorant of something that was common here in the West and known around the world.

But I got over that and remembered the exhilaration of visiting a place where the landscape so strikingly beautiful and imagining how life was for those who lived in Monarch Cave 800 years ago and fed themselves with what they could glean from their immediate surroundings. A visit to Comb Ridge is profoundly moving.

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By rubbing a spear head against stone to form or sharpen it, a groove is gouged very similar to the grooves beside the Procession Panel.

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A Lesson from the Past?

Anonymous — Tue, 20 Dec 2022 16:03:35 +0000

A Lesson from the Past? Anonymous (not verified) Tue, 12/20/2022 - 09:03

Robert L Hohlfelder

Marine concrete from the Roman empire has proven to stand the test of time—and offers insights into ways to combat rising sea levels now

Throughout the Mediterranean Sea, scores of ancient marine concrete monuments, once components of artificial harbors constructed by Roman builders as part of their vast imperial maritime infrastructure, have survived for two millennia and counting.

Modern marine concrete usually survives in the sea for little more than 50 years and sometimes even less. What did Roman builders know that modern harbor engineers did not? This was one of the questions that the Roman Maritime Concrete Study, an international, multidisciplinary project that I organized and co-directed in the first decade of this century, hoped to answer.

Field work was undertaken to collect and analyze concrete cores extracted from submerged structures at various ancient harbor sites in Greece, Italy, Cyprus, Israel and Egypt. The results of this study were published in Building for Eternity: The History and Technology of Roman Concrete Engineering in the Sea in 2014 with a reprint in 2021.

At the top of the page: The last stages of the reproduction of a small marine concrete block using the same materials from the Bay of Naples in the harbor of Brindisi, Italy. Above: A massive concrete block, c. 15x11x4 m, discovered in the harbor of Caesarea Maritima, Israel.

The key ingredient responsible for the amazing durability of Roman marine concrete was volcanic ash or sand from the Bay of Naples, called pulvis puteolanus. It was the binding element in the mortar that, along with aggregate, comprised the concrete itself.

This Neapolitan volcanic ash has a unique chemical composition. When it was mixed with quick lime and seawater, to which rock aggregate was added, the resulting concrete could be placed while still in a liquid state into the sea within a variety of wooden formworks to set quickly and then cure over time. The internal chemical processes that occurred as the concrete cured underwater eventually reduced the porosity of the surface of the concrete block until it became like rock itself. Some scientists have claimed that Roman marine concrete is the most durable substance yet created by humankind.

Obviously, there is not enough volcanic ash in the Bay of Naples region to meet the demands of today’s world. However, material scientists throughout the world are using the data published in Building for Eternity as a starting point in efforts to recreate the chemical processes that occurred in Roman marine concrete that made it so durable—which could become even more important as sea levels rise in response to a warming climate.

NOAA scientists have predicted a sea level rise of at least 2 meters by the end of this century, and this might be a conservative estimate. If this prediction is close to being accurate, all of our coastal cities are at risk of flooding. There will be mass migration of our coastal populations to places like Colorado. But, if a new form of concrete could be used to build durable, long-lived seawalls at critical locations, say along the shores of Manhattan, perhaps our coastal cities might be able to survive.

Such seawalls, of course, would be only one part of future efforts to mitigate the sea level increase that threatens our future.

In addition, perhaps new marine concrete containers that, over time would become indistinguishable from rock itself, might provide one answer to how society safely stores nuclear waste and spent nuclear fuel. On-site steel and concrete barrels, now used as storage containers in scores of locations scattered around our country, are not the answer, since they eventually will leak. New containers made of this impervious marine concrete might well prove to be better receptacles.

After hazardous nuclear material was emplaced, they could then be shipped safely to the Yucca Mountain Nuclear Waste Repository (YMNWR) to be stored in the caverns in this mountain. If so, we would have gone a long way to solving the issue of nuclear waste storage or disposal for perhaps the million years that was the hoped-for goal for the YMNWR. Moreover, there would be little possibility of leakage into nearby aquifers during these millennia.

As I often said to students in my classes, the ancients keep stealing our good ideas. When it comes to improving our marine concrete, we may learn a lesson from the distant past.

Marine concrete from the Roman empire has proven to stand the test of time—and offers insights into ways to combat rising sea levels now.

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