Category: Minnesota

Drilling, Blasting, and Explaining the "Surviving" Stone Holes of Minnesota (Lightning Post)

9/29/2016

I'm going to make this a quick one because I've got a block of (potentially) uninterrupted time this morning and I'm not to going to use a lot of it to discuss stone holes. I wanted to pull a few ideas out of the weeds of the discussion on previous blog posts (here and here) about 19th and early 20th century technologies for blasting rocks. I think an understanding of those technologies will be helpful in understanding how rock-blasting behaviors might be connected to the sizes and placements of the "mystery" stone holes of Minnesota. As I've tried to explain, I'm not asserting that blasting explains all the holes. I'm constructing and fleshing out a hypothesis, rather, that allows us to reasonably ask which holes we might confidently attribute to blasting associated with attempts to clear land and generate angular stone for building.

One of the arguments that I've heard against the "blasting" explanation asks "why would they laboriously drill all those holes and then not blast them?" There are two key assumptions buried in this question that are worth unpacking and discussing.

How Long Does it Take to Drill a Hole in Stone?

First, the issue of effort: was it really that "laborious" to drill stone holes? It is hard physical labor, for sure, but the data we have suggest that creating a hole in a piece of granite is not an all day endeavor. The experimental results shown in the photograph provided by Judi Rudebusch (here, sixth photo) describe eight hours of labor to create two holes together totaling less than an eight inches deep (i.e., less than one inch per hour of work). That's way out of line with other sources of information.

The experiment conducted by Frederick Pohl (reported by Mary Gage and James Gage, The Art of Splitting Stone, 2005:48) resulted in a hole 1 1/4" deep in five minutes with one person drilling;
The Handbook of Rock Excavation (1916:640) reports that a three-man crew can produce a 12" deep hole in 15 minutes;
The world record for single-person stone drilling in competition (3/4" bit, 4 lb. hammer) is 16.34" in 10 minutes;

I know the early farmers of Minnesota would not match the speed and efficiency of professional stone drillers, but the idea that it took hours and hours to produce a hole suitable for inserting an explosive is just wrong. Again, the first-hand account of early 1900's stone drilling in Minnesota from this 1998 article by Tom Trow is useful:

"Gee, whiz, I had to crank the grindstone for ’em to sharpen them chisels. You know, you had a chisel this long [showing about a foot and a half]. And then it was about as big as your finger. And then it was sharp, you know, sharpened, and then you took it like this and then you held it on the stone and then you gave it a crack and, you know, they were experts at turning it, see? And then they turn it, and then they gave it another crack, and that’s the way, after a while, the chisel went down in the stone. And then they dug the scrap out and they kept on drilling until it was about this deep [showing about eight inches]. Then they put powder. . . . in there, black powder, and then if it was a big stone you’d have to make another hole over here and another hole over there. And then they set fire to it and blasted it. And it cracks nice."

The account doesn't say how long it took to drill each hole, but it does tell us that they were using hand drills (apparently with a straight "chisel" bit edge), to produce holes about eight inches deep to accept a charge of black power (gun powder). Those holes would have been triangular, as the triangular shape is produced naturally by the "wandering" of a straight-edged bit. The informant tells us that the chisel was "about as big as your finger," which suggests to me it was less than 1" wide.

Were the Holes Really Left Unblasted?

The second assumption embedded in the question is that the holes were left unblasted. In some cases, that's almost certainly true. Here is an account from a newspaper story I found posted on the website of the Pelican Rapids (Minnesota) Chamber of Commerce:

"Dr. Paul S. Hanna, an Oxford educated historian and native of Fargo, spent boyhood summers on Pelican Lake. As a child he heard the Viking legends and puzzled over holes he found drilled in rocks along the shore of Cormorant Lake. After World War II, he set out by canoe to explore logical Viking river routes north of Winnipeg. He found no mooring stones, no artifacts. But he did find the most awe–inspiring rapids. After nearly being drowned on several occasions, he became convinced no Vikings sailed upriver from Hudson Bay. "The idea," he says, "that Vikings sailed long ships into Minnesota lakes is utterly preposterous. If Vikings came to Minnesota, they most certainly walked."

If Vikings did not drill those holes, who did? Lillian Kratzke of Pelican Rapids says the Cormorant boulders were drilled by her father, Willie Anderson. During the winter of 1908, Mrs. Kratzke says, her father was looking for building stone. The snow was deep and rocks hard to find—except along the lakeshore where the wind had blown away the snow. Willie struggled through three holes, intending to pack them with explosives. Daylight and determination failed him before too long. By the time he got back to the project, spring had come and he found more convenient rocks."

There's one example of stone holes drilled but never blasted.

Logically, however, I think that many of the holes in fact were blasted, but unsuccessfully. The literature from the late 19th and early 20th centuries makes it clear that dynamite (invented in 1867) was a far more effective explosive for breaking boulders than gunpowder. Prior to the use of dynamite, it would have been prohibitively difficult/expensive to use "block-holing" methods to break up very large boulders. Boulders that were mostly buried (so-called "hard heads") would have been very tough cases. I think holes drilled in the tops of these stones were attempts to break them so they could be removed. The mass of the stones would have made the use of gunpowder charges ineffective in many cases, leaving unbroken rocks that have been perforated by seemingly "forgotten" stone holes. In some cases, we have examples where such stones appear to be cracked but were never removed.

I propose that the "unsuccessful blast attempt" idea is a perfectly good explanation for the paired holes in the so-called "Viking Altar Rock" near Sauk Centre, Minnesota. The holes appear to me to be consistent in size, shape, and placement with an attempt to remove a piece of the rock using explosives. I have yet to look at the relevant references for myself, but this is the description of the holes apparently provided by Holand (1946), reproduced in the comments on my last post:

"Four holes have been drilled into the stone in different directions.... The depth and diameters of these holes are not the same. The two horizontal holes are six and nine inches deep, and their diameter is about one and three-eighths inches. The third hole is sixteen inches deep and one inch in diameter. The fourth hole is five inches deep and also one inch in diameter."

I see nothing in that description that is inconsistent with holes drilled for a blasting attempt.

Further Comments

I have a couple of other observations that are relevant to the "stone hole" question. Feel free to comment on these if I'm missing something.

The dimensions of sticks of dynamite are apparently somewhat standardized, with a diameter of about 1.25 inches. The minimum diameter of a stone hole drilled to accept a stick of dynamite, therefore, would have to be 1.25 inches. Round holes of this size can be produced with a "star drill," the bit of which has multiple edges. Star drills produce round holes rather than triangular holes (required to slide the dynamite into the hole), but require more effort than a straight-edged drill to produce the same depth of hole.

In the days before dynamite (i.e., pre-1867), a straight-edged drill would have been preferred because it produces a hole faster. The tendency toward triangular shaped holes would have been inconsequential, as the hole only needed to accept a charge of powder rather than a cylindrical object (a stick of dynamite). The holes could also be smaller than 1.25 inches in diameter.

I propose the following as testable expectations:

1. The triangular holes were intended for gunpowder blasting. These holes may pre-date 1867, but they don't have to. As shown in the Trow article, farmers in Minnesota were still using gunpowder to blast rocks well into the late 1800's and probably beyond. The holes were created using a straight-bit chisel. This tool is more efficient for drilling into stone than a star drill. The propensity to produce triangular holes is inconsequential when the material to be inserted is a powder and a not a solid, cylindrical object. Smaller mean size is likely as there is a positive relationship between bit diameter and drilling effort (larger diameters require more effort) and there is no minimum size constraint imposed by the size of the object to be inserted. The mean diameter of triangular holes is therefore likely to be less than 1.25 inches.

2. Round holes and "star" holes were intended for dynamite blasting. These holes post-date 1867. Because the holes were intended to accept sticks of dynamite, they should be larger than 1.25 inches in diameter.

Incidentally, the "straight bit produces a triangular hole" issue is still with us today. Harold Edwards showed me a pamphlet for the Deltagon Bit SDS-plus that claims that their bit designs produce truly round holes rather than triangular holes. This is important for holes drilled to accept a solid cylindrical object, whether it be a metal anchor or a stick of dynamite. The designers of this drill bit came up with the same solution as stone masons to combat the triangular hole problem: multiple, star-like edges rather than a single chisel-like edge.

More Data on the Rock Blasting Technologies of the 19th and early 20th Centuries

9/28/2016

In continued pursuit of fleshing out and expanding the "Boulder Field Quarry" hypothesis, I've been compiling accounts related to the rock-blasting technologies and behaviors of the 19th and early 20th century. Below is information from four publications discussing blasting subsequent to the invention of dynamite in 1867. They discuss various methods of breaking up boulders, all remarking on the greater effectiveness of dynamite vs. gunpowder.

Some of the sources provide data estimating the charges required to break up rocks of particular sizes, noting that the greater power of dynamite allows one to either: (a) use less of it in a hole bored into the rock; or (b) demolish the rock without even drilling a hole (i.e., by "mudpacking" or "snakeholing"). The 1922 manual says that the charges listed should be doubled if "Red Cross Farm Powder" (which I'm guessing is some kind of non-dynamite blasting powder?) is substituted for dynamite.

The 1916 publication estimates that a three-man crew (i.e., a "double jack" crew with one person holding the drill and the other two swinging sledgehammers) can produce a 12-inch hole in 15 minutes. I'm guessing that's appreciably faster than most of probably conceive of manually drilling holes into hard rock. If you want to see some really fast hole production, watch some YouTube videos of people competing in creating holes using mid-1800's technology: a stone drill, a 4-lb. hammer, and muscle. (Here is a short video of champion driller Emmit Hoyl talking about making holes in stone).

I'm still gathering information. My working hypothesis so far, however, is this:

Early Euro-American settlers of parts of Minnesota (moving into the area around the 1840's) would have encountered a landscape filled with glacial boulders of various sizes. Those boulders would have been a source of building stone as well as an impediment to cultivation. Some of the boulders would have movable as-is by horse and human power. Others, however, would have been impossible to move without first breaking them down in size. They could have accomplished that size reduction by explosive and non-explosive techniques, both of which would include the drilling of holes using stone drills (the straight bits of which, as we have seen, naturally produce triangular rather than perfectly round holes). Prior to 1867, gunpowder would have been the only available explosive. Holes would have been drilled into the tops of boulders to receive a charge of gunpowder. Depending on the size of the rock (and the experience of the person performing the work), blasting attempts may have regularly failed. I'm guessing that some of the intact stone holes may represent those failed attempts to blast using gunpowder. Some early (i.e., pre-1867) attempts to clear fields using explosives may have been largely unsuccessful, especially if the large boulders were mostly buried. Some of those fields may have been re-visited when more powerful explosives became available, while some apparently were not. New immigrants to the area in the late 1800's would not have had any direct memories of the earliest attempts to clear the land. Their choices of which fields to clear may have been influenced by slightly different economic conditions than confronted the earliest Euro-American settlers, and they would have been armed with a better blasting technology (i.e., dynamite).

Transactions of the Essex Agricultural Society (1876:129)

". . . The explosive I now use is Rendrock, an admixture of gunpowder while in a pasty state with nitro-gylcerine. This powerful explosive, though well known and very generally in use by contractors on public works, is yet so little known by farmers in general that I think it will be worth while for me to give them an introduction to it, as its use enters so largely into the economy of handling boulders.
" . . . As will be seen, it is over twice as costly as common blasting powder, but, as every farmer knows, the great cost in blasting is the drilling, and this is where the saving comes, as it will do as much execution as gunpowder in a hole of one-third capacity. . . . The extra power becomes of value in enabling one to do in a single blast what gunpowder would require two to accomplish."

The New International Encylopaedia (1905:163)

"The first attempt to blast rock by the use of an explosive is commonly credited to Martin Weigel, a mine boss at Freiberg, Saxony, and is said to have occurred in the year 1613. . . . it is certain that by 1634 to 1644 the use of gunpowder in mining operations was quite generally known in Germany. From that country the process was taken by German minders to England in 1670, and to Sweden in 1724. Until 1685 the drill-holes were stopped with wooden plugs, but in that year clay-tamping was employed in Saxony. In 1791 sand-tamping was first used. Hand-drilling with cone and crown drills was used until 1759, when the modern chisel-edge drill was introduced. . . . In 1863 nitroglycerin, and in 1867 dynamite, were first used as explosives in blasting operations. . . .
"Modern blasting operations may be divided into three classes: (1) small-shot blasting, in which comparatively small volumes of rock are moved at a single blast; (2) blasting by mines, in which large masses of rock are broken up by a single heavy blast; and (3) surface-blasting, in which the explosive is placed on or against, or simply near to the rock to be broken up, and which is possible only with very high explosives. Small-shot blasting is employed in the great majority of quarrying, mining, and engineering operations. It consists in piercing the rock with a comparatively small number of drill-holes from 1 1/4 inches to 3 inches in diameter and from 18 inches to several feet in depth; charging these holes with explosives, generally blasting powder or dynamite, with the proper fuse or electric-wire connections; tamping the space above the explosive with earth, sand, clay, or water, and finally firing these charges by means of a time-fuse or wires from an electric battery or magneto-machine. The relative location of the drill-holes, their size and depth, and the amount of explosive used vary according to the object which it is sought to accomplish by the blast. Where the purpose is merely to break up the rock in the most efficient manner for its removal, as in excavating a foundation, the holes will be placed quite close together and heavily charged, so as to shatter the rock thoroughly. In quarrying, where the object is to loosen the rock in large and regularly shaped masses, the holes are arranged in rows and lightly charged, so that the explosion will split the rock along approximately definite lines without shattering it."

Handbook of Rock Excavation (1916:636-637)

"There are three ways of breaking up a boulder with explosives: (1) block-holing; (2) mud-capping; and (3) undermining.
  Block-holing consists in drilling a shallow hole in the boulder and exploding a small charge of high power explosive in the hole.
Mud-capping, or "bulldozing," or "adobe (or dobe) shooting" consists simply in firing some dynamite on top of the boulder, after covering it with a shovelful of earth, preferably wet clay.
   Undermining or "snake holing" consists in boring a hole in the earth and firing a charge of dynamite in the hole directly beneath the boulder.
   Block-holing is obviously the most effective way of using the explosive. It is surprising how small a charge of 75% dynamite in a block hole will break a huge granite boulder. The cost of drilling is greatly reduced wherever pneumatic hammer drills are used. . . .
   A Du Pont catalog contains Table LLX giving chages of 40 to 60% dynamite for boulder blasting."

"Figs. 146, 147 and 148, illustrate the proper methods of mudcapping, snakeholing and blockholing.
The tests described below, carried on by the Bureau of Mines, were made to determine the comparative energy expended by explosives under water and in the air, and by various methods of shooting. The test showed very conclusively that the block-hole method of breaking boulders and large fragments of rocks is very much superior to and more economical than the mud-cap or "adobe shot" method of breaking, which is so commonly practiced."

"Block Hole Drilling. Comparative methods and costs as stated by Mr. Charles C. Phelps in Engineering and Contracting, April 7, 1915."

Farmer's Handbook of Explosives (1922:54)

Minnesota Stone Holes and 19th Century Technologies for Breaking Rocks

9/27/2016

The purpose of my initial post on the "Boulder Field Quarry" model for the stone holes of Minnesota was to provoke some thought and discussion on how we might generate plausible, well-warranted explanations for the holes. It has succeeded so far, I think, in at least clarifying some of the questions we might ask. I didn't propose the model as some kind of final statement, but rather as a hypothesis that could be used to generate falsifiable predictions. As the discussion on the post clearly shows, the Boulder Field Quarry model as I initially phrased it is too narrow, not including non-blasting historic-period behaviors associated with creating holes in rocks.

I'll eventually formulate an expanded version of the hypothesis, trying to take into account what's being discussed. In the meantime, I thought I'd share some of what I've come across as I've been exploring the world of 19th century technologies for breaking rocks. I've been particularly interested in collecting historic information about the use of gunpowder and dynamite for blasting boulders. Rather than wait until some mythological day when I'll be able to synthesize everything, I'm going to employ the "thinking out loud" method and present the stuff as I find it. I hope to eventually create a summary of general changes in behaviors and technologies for breaking rocks that will provide some context for the Minnesota stone holes. But for now here are a few pieces of raw information.

Philosophical Magazine (1808:99-100)

"About ten years ago an experiment was made in Cornwall upon a loose rock on the surface, and sand was blown out without any effect having been produced: an equal quantity of gunpowder, confined by a small quantity of tamping, broke the rock; which proved that the resistance was far inferior to that of the common mode."
. . .
"M. Pietet, it is said in the same article of the Philosophical Journal for July, has conceived that a more effective explosion for the purposes of mining might be obtained by leaving a partial vacuity, or by the chamber not being completely filled by gunpowder."

The Edinburgh Encyclopaedia (1832:553):

"The process of blasting rocks, or stones, consists in boring a cylindrical hole, about 10 or 12 inches deep, in the rock by means of a chisel for that purpose. The lower part of this hole is filled with gunpowder. The upper part of the hole is then filled up with fragments of stone, firmly rammed together; a hole being left through these materials, by the insertion of an iron rod, which is turned round during the operation of ramming. This hole is next filled with powder, and a match is applied to it in such a manner, that the operator has time to run out of the reach of the fragments of the rock."

Farm Echoes (1883:45-46):

""Has any one present had any experience with Dynamite, or Giant Powder, in clearing rocks from land? If so, will he give us the result"
"Mr. Starr, of Litchfield, can give us some information on that point."
Mr. Starr-- "I will say that I know but very little about this matter, except from results as shown on my fields. A Mr. Parmalee, who makes it his business to blow up rocks with dynamite, passed my place, and I asked him to experiment in one of my fields, which I expect to clear next summer. There were a large number of rocks in the field, such as could not very well be blasted with powder, and I asked him what he could do. . . . I pointed out a rock ten and one-half feet long, five and one-half feet wide, and nine or ten inches in depth--such a rock, as any one will see, would be difficult to blast with powder, because there is not depth enough to drill into it. I took out my watch, and in precisely seven and one-half minutes from the time he began to work the rock was in atoms. . . . I have used many kegs of gunpowder, during my six years' experience, in blasting rocks, and am free to say, that the same amount of work could not have been accomplished with ordinary blasting powder, and the same number, in less than a month."

Molds of Minnesota Stone Holes (Lightning Post)

9/26/2016

I'll have more to add soon to the discussion of stone holes currently taking on yesterday's post about the "Boulder Field Quarry" hypothesis. For now, however, I just wanted to pass on (with permission) some images sent to me yesterday by Judi Rudebusch. As you can tell from her comments, Rudebusch has been collecting information about stone holes for some time. My goal in posting these is so we can refer to them in discussions. I'll caption each one with the information she gave me (Judi, please correct me if I get anything wrong).

Two molds made from stone holes: the Hansen mold (left) and the Lewno mold (right).

Detail of the terminal end of the Hansen mold.

Image of the Lewno mold showing "shelving."

A quarried rock in a basement on the Ohman farm. Two bisected stone holes are clearly visible (Rudebusch says there are three but I can only discern two in the photo). These holes would have presumably been employed in the "plug and feather" method of splitting rock.

Another bisected stone hole preserved in a foundation rock on the Ohman farm.

Results of an experiment in making stone holes with hand chisels.

Endoscope image of the top wall of one of the experimental stone holes showing the state of the mineral grains in a "new" hole.

Minnesota Stone Holes and the Boulder Field Quarry Hypothesis: I Dare You to Prove it Wrong

9/25/2016

At the risk of stepping in it (again), I'm writing another post about stone holes.

You heard me: stone holes.

My last post on the subject asked why we should assume that hand-chiseled holes (which are irregular or triangular in shape rather than perfectly round) are medieval in age. There are several pieces of information (including experiments and first-hand accounts) that leave little doubt that the hand-chiseled holes being created in Minnesota in the 1800's and early 1900's would be difficult to distinguish from any holes left by a Norse expedition hundreds of years earlier. The discussion on that post didn't convince me that there's a good positive case to be made for the medieval origin for any of the stone holes: the work to develop and apply a reliable methodology for discriminating stone holes based on their intrinsic characteristics apparently hasn't been done yet.

I thought it might be fun to approach the problem from the other direction: let's develop a falsifiable hypothesis that all of the stone holes are of modern (i.e., post-Columbus) origin. I'll call it the "Boulder Field Quarry" hypothesis. I didn't invent this explanation, of course, but considering it as a formal hypothesis will be a useful way to demonstrate how you use an explanatory model (an explanation/description of how variables fit together) to derive falsifiable expectations that you can compare to empirical data. If it's possible to prove a hypothesis wrong but you can't do it after repeated attempts, you can start to have some confidence that you might be onto something. Here it goes.

Hypothesis: All of the stone holes found on boulders in Minnesota were produced by post-Columbus Euro-American settlers for the purposes of blasting the boulders into smaller pieces.

Glacial boulders in Minnesota were useful sources of stone for the Euro-American who populated the region in the 1800's. Holes chiseled or drilled into boulders were packed were filled with black power, gun powder, or dynamite. The explosives were ignited to break the boulders into smaller pieces which could be removed to clear fields and/or be used as building materials.

In The Art of Splitting Stone: Early Rock Quarrying Methods in Pre-Industrial New England 1630-1825 (2005), Mary Gage and James Gage discuss how this technique was used by German immigrants to New England in the late 1700's and early 1800's (pp. 24-25). Gage and Gage (pg. 25) describe round blasting holes with a diameter of about 1 3/16" (about 3 cm) and depths ranging from 4 to 20 inches (about 10-51 cm). New England blasting holes created after 1825 are slightly larger, ranging in size from 1.5-2 inches (3.8-5 cm) (pg. 25). Gage and Gage also note that "Generally, the hole was drilled into the top center of the boulder . . . Some surviving examples of blasted boulders have two or more blasting holes. The evidence indicates that an additional blast hole was drilled when the first blast was insufficient to break the whole boulder apart" (pg. 25).

Text Expectations: The placement, diameter, and depth of stone holes in Minnesota should be consistent with their creation for the purpose of blasting rocks. Based on descriptions of boulder field quarry blasting in New England discussed by Gage and Gage, the following statements should be true:

Boulders with one or more stone holes are too large to easily move in one piece or too large to use in the construction of building foundations;
Stone holes are located on the top surfaces of boulders in locations suitable for blasting the entire boulder or removing significant pieces of the boulder;
Stone holes are in the range of 3-5 cm in diameter;
Stones holes are in the range of 10-60 cm in depth;

The test expectations are pretty simple. They can be refined if there's additional information out there about patterning in stone holes associated with boulder field quarry blasting.

In the comments to the previous stone hole post, I mentioned repeatedly the need for a stone hole dataset that could be analyzed. This is why. The boulder field quarry model produces specific expectations for patterning in the placement, size, and depth of stone holes. In other words, it makes predictions which can potentially be shown to be false. Testing those predictions requires empirical data that can be used to quantify and characterize the stone holes. How wide are they? How deep are they? Where are they located on individual boulders? Are there any examples of small, intact boulders with stone holes?

Can the "medieval Norse origin" stone hole model produce a set of falsifiable predictions? I don't know. If so, I have yet to see those predictions clearly articulated.

That's one reason why the boulder field quarry hypothesis should be the null hypothesis. There are several others: it accords with multiple first-hand accounts, it's logical, and it fits with experimental, archaeological, and historical data from other areas. If you can prove that the stone holes weren't for blasting, I'm prepared to consider alternatives. But first you either have to show me why this explanation doesn't work (citing "because the Kensington Rune Stone" exists isn't going to cut it, either, for reasons I've already beat to death) or develop an alternative model that's also falsifiable. What characteristics of these stone holes indicate they weren't created for blasting rocks?

Figure from Tom Trow's "The "Mooring Stones" of Kensington" (Minnesota History, Fall 1998; http://collections.mnhs.org/MNHistoryMagazine/articles/56/v56i03p120-128.pdf)

Calcite Weathering and the Age of the Kensington Rune Stone Inscription (Lightning Post)

9/13/2016

As my Forbidden Archaeology course descends into the meaty part of the syllabus, the interesting "fringe" topics I'd like to write about are piling up to the point where I'm feeling buried. There was already a backlog, but now I'm finding myself listening to presentations and interviews (rather than music) on my walks to and from work. When I get to my lab, however, I've got people to manage and a hundred other things to do to move my actual research forward -- I just haven't been able to make the time to hole up and spend a few hours composing a thoughtful blog post. One of the reasons I like to write is that the process of writing helps me organize my thoughts. So it's a bummer that I'm finding less time to write during the semester when I'm most immersed in "fringe" claims.

Rather than let things remain unwritten, I'm going to try a "lightning round" approach where I quickly summarize an idea: short and (hopefully) to the point. These posts won't be works of art, but will (1) provide a place for discussion for those who are interested in a topic and (2) provide an organized summary that I can return to. So don't beat me up if I leave something out or fail to appreciate some nuance: it is what it is.

Now onto the topic.

Harold Edwards, a professional geologist and scheduled Forbidden Archaeology participant, sent me some information on the weathering of calcite as it relates to evaluating the age of the inscription on the Kensington Rune Stone (KRS). Edwards told me that I could "use these pictures and this information as you wish." I'll quote Edwards directly when so you'll know which words are his and which are mine.

First, some definitions:

Calcite is a common carbonate mineral that is one of the principal constituents of limestone and marble. It has a Mohs hardness of 3 and dissolves in acid.

Greywacke is a variety of sandstone. Sandstone has a Mohs hardness of 6.5 to 7. The susceptibility of sandstones to acid depends upon the minerals holding the sand grains together.

The different hardness and weathering properties of calcite and greywacke are important to evaluating the age of the inscription on the KRS. I have modified an image of the KRS (taken in 1995 and sent to me by Edwards) to show the location of the calcite deposit on the front face of the KRS. According to Richard Nielson and Scott Wolter (The Kensington Rune Stone: Compelling New Evidence, 2006, p. 17), the calcite layer is 1-2 mm thick and was deposited millions of years ago "along the joint fracture system [while the rock was still attached to its parent] in solution, parallel to the face side of the stone." (In his email, Edwards stated that the calcite layer was about 3 mm thick).

A 1995 image of the Kensington Rune Stone, modified to show the distribution of calcite on the front face (original image from Harold Edwards).

The inscription on the KRS extends into the calcite deposit. Given that calcite is more susceptible to weathering than greywacke, one would expect that the portion of the inscription in the calcite would be more weathered than the portion in the greywacke. Neilsen and Wolter (2006: 17) say this is, in fact, the case:

"Microscopic examination using reflected light revealed that the characters carved into the calcite were less distinct and appeared to be more weathered than the characters carved into the graywacke. . . . Further study of the weathering of the characters within the calcite area might yield additional information about the relative age of the inscription, but currently the only tests available are invasive and would deface the inscription."

In his email, Edwards claims that the portion of the inscription in the calcite is much less weathered than one would expect had the carved runes actually been exposed to 500 years of weathering:

"The inscription is about as sharp as the day it was carved. Look at the word spacer--the colon-like double dotted letter. There is an almost perfect impression of a conical punch. The surface of the calcite layer shows the granular texture that is typical of weathered calcite so it was weathered for some time. The letters are smooth showing virtually no weathering."

Image of the KRS in 2003 showing the inscription in the calcite area (image from Harold Edwards)

Edwards also sent me some images of marble tombstone from 1881 to illustrate the effects of above-ground weathering on calcium carbonate rocks. Edwards wrote the following:

"Marble is almost completely made of calcite. Rainwater absorbs carbon dioxide from the air to become slightly acidic and over time dissolves away the calcite. In the Kensington area this happens to marble tombstones at a rate of 6mm/1000 years. In other words in the 500 years between 1362 and 1898 the calcite layer would have been obliterated."

Comparison of a tombstone inscription from 1881 with the inscription on the KRS (image from Harold Edwards).

Anyone who has visited an old cemetery understands that inscriptions in limestone and marble have not faired well over the last 150 years. I had always heard that airbone pollutants associated with the Industrial Revolution increased the acidity of the rain, hastening the deterioration of marble and limestone. Obviously, the KRS would not have been exposed to the same rains as the 1881 tombstone. Even if the KRS was "protected" underground, since it was carved, however, it would not have been immune to the effects of weathering. Edwards has sent me a lot of information on the below-ground weathering of calcite, but I haven't had time to digest it yet. That will have to wait for another lightning post. Or for Edwards to explain it to us here . . .

How Many Norsemen Does it Take to Make a Triangular Hole in a Rock?

9/9/2016

If you're interested in the issue of stone holes in the Upper Great Lakes and whether or not some of them were made by members of a medieval Norse expedition, you are probably familiar with the work of Bob Voyles. As I wrote last Friday, I've invited Voyles to prepare a guest blog post about his ideas, perhaps the first in a series of "Forbidden Friday" posts. There has been some back and forth in the comments on that post, so I thought I'd make a new post to pose some of my own basic questions/thoughts about the stone hole issue prior to Voyles' guest post. I want to make it clear that I'm not a stone hole expert, and I haven't spent a lot of time looking into Voyles' claims (i.e., it's possible he or someone else has already addressed these questions).

Confronted with the claim of a Norse origin for some of the stone holes, my first question is "how do you know the holes were made by the Norse?" You can't directly date a hole in stone, after all, and there are several possible reasons for creating holes in stones in the first place. The leading "mainstream" explanation for most of the holes, as described in this 1998 article by Tom Trow, is that they were created for the purposes of blasting the rocks apart so the pieces could be used for the foundations of buildings. Trow (pp. 127-128) quotes an older resident's description of how and why the stone holes were created, by hand, with iron or steel chisels:

"Gee, whiz, I had to crank the grindstone for ’em to sharpen them chisels. You know, you had a chisel this long [showing about a foot and a half]. And then it was about as big as your finger. And then it was sharp, you know, sharpened, and then you took it like this and then you held it on the stone and then you gave it a crack and, you know, they were experts at turning it, see? And then they turn it, and then they gave it another crack, and that’s the way, after a while, the chisel went down in the stone. And then they dug the scrap out and they kept on drilling until it was about this deep [showing about eight inches]. Then they put powder. . . . in there, black powder, and then if it was a big stone you’d have to make another hole over here and another hole over there. And then they set fire to it and blasted it. And it cracks nice."

Trow's informant (Emil Mattson) was born in 1897, and therefore would have been describing creating stone holes using hand chisels in the early 1900's.

If I understand Voyles correctly, he claims that one can differentiate stone holes created in the 1800's and 1900's from those created by the Norse because of differences in (1) weathering and (2) form. With respect to weathering, Voyles states that the edges of what he interprets as medieval stone holes show significantly more weathering on their edges than those that were obviously made by modern drills. On this page he shows what he describes as aging differences between a "modern" stone hole and one created by the Norse.

Screenshot showing Voyle's comparison of stone hole weathering.

With respect to shape, Volyes points to differences in the regularity of holes created with modern drilled versus those created by hand chisels. In a January 2016 article titled "In Defense of the Kensington Runestone: Stoneholes," Voyles makes the following statement:

"The medieval stoneholes are slightly triangular because it is not possible to make a perfectly round stonehole with a hand chisel. Later modern drilling could make perfectly round holes, and this is how old and new can be distinguished from one another."

I think Voyles is correct that are groups of holes made using different techniques. My issue comes with equating "triangular" or "hand-chiseled" with "medieval." A little searching online turned up some descriptions of early American stone quarrying methods that are useful, I think. The first quote is from the 2005 book The Art of Splitting Stone: Early Rock Quarrying Methods in Pre-industrial New England 1630-1825 (Mary Gage and James Gage) in a section titled "Hammer Drilling or Triangular Hole Method" (page 48):

". . .Triangular holes are documented at archaeological sites in Massachusetts, New Hampshire, Delaware, and Great Britain. Archaeological, historical, and experimental evidence has demonstrated that the triangular holes were cut with a straight edge chisel being rotating approximately 60 degrees between hammer strikes. These holes come in a wide variety of diameters and depths.
Frederick Pohl in his book The Lost Discovery has documented and researched several triangular hole sites found in stone outcroppings along the tidal waters and bays on Cape Cod . . . Mr. Pohl felt a straight-edged chisel rather than a plug or star drill was used to drill/cut the triangular hole. To verify his theory, he conducted an experiment. He and two other people, "taking turns leisurely cut a hole 1 1/4 inches deep in five minutes. We found we could not make a round hole with a straight-edged chisel. All our attempts resulted in triangular holes with the corners rounded.""

Gage and Gage point to other interesting accounts of using hand chisels to create stone holes. A 1904 book by Halbert Powers Gillette titled Rock Excavation: Methods and Cost is quoted in this report by James Gage:

"Hammer Drilling. – The common weight of hammer for one-hand drilling is 4 ½ lbs; for two-hand or three-hand drilling 10 lbs. The striking face must be flat or slightly rounding, and smaller than the stock of the hammer. The hole is started on a solid and squared surface, with a short drill, for the longer the drill the less effective the blow. Light blows are struck at first. The bit is turned one-eighth of a revolution after each blow to insure keeping the hole truly circular. But in spite of this precaution most hand-drilled holes are three-cornered, or “rifled.”"

Based on the fact that we've got multiple accounts demonstrating that hand chisels were commonly being used to produce holes in rocks in the northern United States at least into the early 1900's (including in Minnesota), and that such methods typically produced triangular holes . . . on what basis could one claim that some triangular/irregular stone holes were created by the medieval Norse? What is the positive evidence? How could you separate out the Norse holes from all the others that we know were being created?

As Voyles suggests, weathering could be a way to go. If similar tools were used to create similar holes, there's still at least the theoretical possibility that one could differentiate stone holes created in the 14th century from those created in the 19th or 20th centuries by looking at the weathering of exposed surfaces. As Voyles stated in his comments on my blog about the Sauk Lake Altar Rock, "multiple hand-chiseled holes in this rock can be compared to the mineral or mica decomposition of the late 1800's stoneholes to see that they are extremely aged by comparison." I think there's potentially a significant difficulty here, however, if we depend on macroscopically-observable "weathering" to assign relative age. The descriptions of steel chisels "dancing" around in the holes as they're created suggests to me that the edges of hand-chiseled holes might be battered as they are created (rather than smoothed gradually by mechanical weathering). To my eye, for example, the triangular hole shown by Gage and Gage in Figure 20 (page 49) appears to have a battered/smoothed lip. Perhaps there would be a way to look at some microscopic characteristics of the stone and say something about aging. You'd have to have good controls for that, however. If I were trying to build a case that some of these stone holes were created by medieval Norse, I'd start working on that aspect and looking for other ways to differentiate them from modern holes.

That's my two cents on stone holes for today.

The Remains of Little Crow

4/28/2015

Little Crow.

Little Crow (1810-1863) was leader of the Mdewakanton Dakota, a Sioux people with a historic homeland in what is now Minnesota. He is perhaps most famous for his roles in the 1851 agreements (the Treaty of Traverse des Sioux and the Treaty of Mendota) that ceded much of southern Minnesota to settlement by Euroamericans and the Dakota War of 1862. This was a short and brutal conflict that ended with hundreds dead and many Dakota in exile. For their roles in the conflict, 38 Dakota men were hanged on December 26, 1862. The execution was the largest mass execution in U.S. History (source).

Little Crow, not among those captured and executed, was killed in a shootout with white settlers (who were apparently out to pick raspberries) in July of 1863 near Hutchinson, Minnesota. The story of Little Crow's remains is interesting to me for two reasons. First, it contributes to our understanding about what the phrase "double row of teeth" might have meant in the nineteenth century. Second, and more importantly, it is a vivid example of how Native Americans were regarded in this country in the 1800s and how their physical remains were treated.

The body, clearly that of a Native American, was not immediately identified as that of Little Crow. That didn't stop the locals from abusing it, however. I haven't yet tracked down original accounts of the events that followed the shooting of Little Crow, but I found a 1962 article titled "The Shooting of Little Crow: Heroism or Murder?" by Walter N. Trenerry that appeared in Minnesota History:

"The search party callously removed the dead Indian's scalp and went back to town. Later that day the body was
loaded on a wagon, brought into Hutchinson, and there tossed into the refuse pit of a slaughterhouse, like an animal carcass.
About a week later some local ghoul pried the corpse's head off with a stick and left this gruesome object "lying on the prairie for some days, the brains oozing out in the broiling sun."
No one knew at this time who the victim was. He appeared middle-aged; he had curiously deformed forearms; and he had the physiological oddity of a double row of teeth. Although several Hutchinson residents thought that the man looked familiar to them, no one seemed able to identify him positively."

The Wikipedia entry also states that "His body was dragged down the town's Main Street while firecrackers were placed in his ears and nose." If you have any doubt of the validity of the claim that Native Americans were treated with extreme brutality in this country in the past, I encourage you to go and read some newspapers from the 1800s. The language and what it describes are appalling.

Until I get the original sources cited by Trenerry, I won't be able to see exactly what the 1863 accounts say about a "double row of teeth." As I have written previously (e.g., here, here, and here), context and exact wording are important. I found one later newspaper article that suggests to me, however, that the identification of a "double row of teeth" was based on a misinterpretation of the normal arrangement of tooth root sockets (alveoli) in the maxilla. A story in The New York Times (April 14, 1879) reads as follows:

GHASTLY RELICS.

The St. Paul (Minn.) Pioneer-Press prints the following communication:

LANESBORO, Fillmore County, March 28.--The Pioneer-Press of March 20 states that Dr. Twitchell, of Chatfield, has presented the State Historical Society with a part of Little Crow's skeleton. The skull of that famous chief is now the most prized relic in my collection of Indian curiosities. It was presented to me by an esteemed friend, the Hon. James Farmer, of Spring Valley. Mr. Farmer had it secreted in his house for several years, hidden in a nook covered with lath and plaster. I am now corresponding with Mr. Lamson who shot Little Crow, and hope soon to possess the gun with which he was killed. The sister of Little Crow's slayer (Mrs. Frank Ide) lives within four miles of Lanesboro. The skull is fractured in places where the stake was thrust through when the citizens of Hutchinson carried it though the town in triumph. The alveolar process (which held the teeth) are double, showing that the chief must have had a double row of teeth in the upper jaw. I have the skulls of "Spotted Horse" and "Two Fathers." Also many relics from the scene of the Sioux-Pawnee massacre on the Republican River in 1872, which I gathered before the Indians were all dead. D. F. Powell, M. D.

This account suggests to me that Dr. Powell made the same basic anatomical mistake as Bigfoot researcher Daniel Dover: he interpreted the parallel rows of root sockets associated with maxillary molars as evidence that two rows of teeth had been present in life. Notice how he specifies that a "double row of teeth" was present in the upper jaw, not the lower jaw (the mandibular molars typically only have two roots). I could be wrong, but I think it's likely that Dr. Powell just didn't know what he was looking at. He would certainly not be the first physician in the 1800s (or today, for that matter) to demonstrate a less-than-perfect knowledge of human skeletal anatomy.

Apparently Little Crow's remains eventually ended up in the care of The Minnesota Historical Society. This website shows a photo of what is apparently Little Crow's scalp in the Smithsonian. The remains were returned to Little Crow's grandson in 1971 and subsequently buried.

Another thing worth knowing: the bodies of the Sioux executed after the war in 1862 were used for medical study. William Worrall Mayo, father of the brothers who founded the Mayo Clinic, received the remains of Mahpiya Okinajin (aka He Who Stands in Clouds aka Cut Nose) and reportedly kept them in a rendering kettle in his home and used them to teach his sons anatomy. The remains were returned to the Sioux in the 1990s. A piece of skin from Cut Nose, found curated at the Grand Rapids Museum, was also returned for reburial.