Author: Karen

December 2008

While conducting research last week at U of M’s library in Ann Arbor, I was very excited about all the agate genesis articles I was able to locate. I concentrated mostly on articles published in the last decade. However, I could not resist the temptation to print off a 66-page leaflet published by the Field Museum of Natural History in Chicago in 1927. The leaflet was written by Oliver C. Farrington, the Curator of Geology and is entitled: “Agate Physical Properties and Origin.” It is amazing that in the last 80 years, our knowledge of agates has not changed very much. Below are some excerpts from the leaflet.

“Agate is a variety of chalcedony chiefly distinguished by its banded or variegated structure and coloring. Its banded appearance is due to the fact that it is made up of a great number of exceedingly thin layers which appear as bands in cross section. As seen by the naked eye, these bands differ considerably in width, some seeming no wider than a line, while others may be a quarter to a half-inch wide. In reality, all these bands are made up of still finer ones, the individuals of which can be seen only with a microscope. In a section of agate only one inch in thickness, Sir David Brewster counted 17,000 such individual bands.”…

…“The most common and characteristic form of agates is one which in cross-section resembles an old-time bastion, a defensive work characterized by curving contours and salient angles. Agates of this pattern are known as “fortification: agates (Plate 1).” …

…”Agates are generally formed in cavities in volcanic rocks. In the escape of gases and vapors from such rocks on cooling, cavities similar to those seen when pasty substances are heated are often formed and remain open when the rock has cooled. The cavities are usually spheroidal in form or, more specifically, are often shaped like an almond, whence the term amygdaloidal, from the Greek word for almond, is applied to them. The size of these cavities is also often about that of the almond but they may be much lager. It is in cavities like these that agates are chiefly formed, occurring as a filling that takes the shape of the cavity. Being of very tough material, which resists both physical and chemical corrosion, the agate nodules (the lumps or masses formed by the filing of the cavities) are usually left intact after the rock about them has decomposed and hence agates are often found in soil or in beds of streams. In the latter case, they may occur far removed from the place of their origin. The size of the agate nodules varies according to the size of the cavity in which they are formed. From very minute, they run up to weights as high as 4,000 pounds.”…

…”No one who gives much consideration to the subject of agates, can fail to be impressed with the difficulty of explaining how they are formed. They appear to be made up of successive layers deposited on the walls of the interiors of cavities, each layer toward the interior being younger than the one preceding. Sometimes the process of deposition appears to have continued until the cavity was entirely filled, but in other cases, a vacancy still remains at the center. If the above is the method of formation, it is difficult to understand why the deposition of the first layer, or, at least of the first two or three layers, would not close the cavity to succeeding deposits.

Various attempts have been made to answer this question. Haldinger, a German geologist, writing about 1849, made the suggestion that the moisture ordinarily found in rocks, the so-called “mountain moisture” would “sweat” through into the cavities and that successive solutions of silica would thus enter through diffusion. This explanation seemed adequate to many investigators, but others have agreed with Noeggerath, a contemporary of Haidinger, that it is doubtful if solutions would continually enter the cavity in this manner, especially as the outer layers of agate nodules are known by agate cutters to be particularly hard and impervious to liquids. As a better explanation Noeggerath called attention to an apparent canal or conduit which can be seen leading outwards from the interior of most agates and which he believed remained open during the formation of the agate for the admission of percolating waters. … In some agates, several such so-called entrance canals are to be seen, but in some unfortunately for the theory, none can be found. Moreover, it is difficult to understand why such canals, if they ever existed, would remain open. The above theories, however, are the only ones that until recently have seemed at all worthy of credence as possible explanations of the manner of formation of agates and for many years were accepted by most investigators.”…

…”It is only recently that a theory for the formation of agates has been proposed which gives a totally different explanation from the above and which is in many respects more satisfactory than the earlier views. According to the latter theory, the rock cavity in which the agate is formed, first becomes more or less filled with silica in a colloidal (jelly-like) condition. In such a colloid a banded structure can be produced by processes, which can be illustrated with ordinary gelatin.

The following experiment as described by Ostwald in 1896 illustrates this process. If silver nitrate is introduced into a colloid which contains ammonium bi-chromate, silver chromate (a red salt) is at once formed, but it does not at first appear in a solid form. It is still dissolved. Gradually, however, through the continual formation of silver chromate, the solution becomes so concentrated that it must somewhere separate out. This separation takes place first at an edge. Then all the super-saturated substance makes its way to this edge and likewise separates out. An essential consequence of this is that adjacent to this deposit, a zone is formed which is free from silver chromate. But this zone also does not contain ammonium bi-chromate, for this has been used up by the silver nitrate. Here, then, no new silver chromate can form and the zone becomes colorless. The excess of silver nitrate pushes on, however, and by the same reactions forms a second band of silver chromate and a color-less zone. Continuation of this process gives a banded structure.”…

…”Besides explaining the banding, this view of the method of formation of agates also indicates why agate nodules are often hollow in the interior. Drying of the colloidal silica causes a shrinking in bulk which would often leave such a hollow. The theory also explains the frequent occurrence of quartz crystals in the interior of agates. Crystals cannot form in colloids on account of surface tension, but when the tension is relieved at the hollow interior of the nodule, complete crystallization can take place there.” …

…”According to the present view, then, fortification or common agates originate from a filling of hollow spaces in rocks by a silica colloid (jelly), within which an iron salt compound has been rhythmically deposited.”

November 2008

Probable Economic Impact of the Lakeshore

The most direct economic impact of the proposed lakeshore will be upon the forestry and recreation industries of the Upper Peninsula region. These industries and associated economic opportunities are examined here.

Forestry

Forest industries are the largest single source of employment in the Upper Peninsula region. In 1960, thee were an estimated 9,900 engaged in logging, and 8,300 in forest product manufacturing, making a total of 18,200 full-time equivalent workers. This was about 18 percent of the total workforce of approximately 100,000. The gross income of the Upper Peninsula forest industry was estimated at $109 million in 1960.

The area around the proposed lakeshore is even more dependent upon logging and forest manufacturing operations than is the Upper Peninsula generally. Mills now drawing partially upon raw material from the “recreation zone” employ 190 full-time and 66 part-time workers. Their payroll is reported at $875,000. There are, in addition, many mills and plants drawing raw material from the general vicinity. Although not currently using pulpwood from the Upper Peninsula, the Kimberly-Clark Paper Mill at Munising employs 500 to 600 workers. Within a radius of 70 miles of the proposed lakeshore, there are 400 to 500 men employed in the woods with annual payrolls in excess of $1,000,000.

Because of regeneration of forest stands in the Upper Peninsula region, new wood processing plant development, there is now taking place and is expected to continue. The proposed Pictured Rocks National Lakeshore is not expected to have a substantial influence on the possible location of new wood-using plants in the region, or on the operation of large plants that are there now. There will be, however, increased economic pressure on small mills operating in the immediate vicinity, if timber harvest is suspended in the “recreation zone.”

Tourism

Two recent estimates of 1960 tourist expenditures in the Upper Peninsula average to $110 million. Other studies have shown 25 to 27 percent of tourist expenditures becoming direct personal income. On this basis, the direct incomes to operators and employees from tourism in 1960 were $27,500,000. In terms of $5,000 jobs this is an employment of 5,500 full-time equivalents, although, like forestry, it is probable that several times as many individuals had at least part-time employment. Thus, tourism in the Upper Peninsula is a major source of employment. Rapidly increasing national demand suggests that tourism could be a still larger economic contributor to the region.

Alger County tourist expenditures have been as high as $2.9 million in 1957 but dropped to $1.3 million by 1961. The drop was part of a stagnation or decline across the entire region. This decline is confirmed not only by year to year estimates of total expenditures but by traffic counts over the region, crossing at Mackinac Bridge and attendance at state parks.

The proposed Pictured Rocks Lakeshore would be expected to make its major contribution to Upper Peninsula tourism by helping to strengthen the “image” of this “north woods and lakes country” as a tourist destination area. The lakeshore would add a major destination point at which recreation services – things to see and do — would be available. As a part of the National Park System, it would give national status to the Upper Peninsula. The lakeshore would be a significant addition to the complex of regional attractions: from Mackinac Bridge, Mackinac Island, Soo Locks and Tahquamenon Falls in the east; to the copper mines, ghost towns and Fort Wilkins of the Copper Country (northwest); the Porcupine Mountains State Park in the west; plus a wide variety of resorts and private recreation developments throughout the region. Finally, the positive action of developing the proposed lakeshore could be expected to help spark constructive developments by private firms in the tourism industry.

Estimates of the gross income and employment due to the proposed lakeshore vary depending upon the future character of the Upper Peninsula’s tourism industry. If the industry retains its present relatively passive nature, added gross income to the region might be only $2,967,000 ten years from the present, generating an additional 167 full-time job-equivalents earning an average of $5,000 per year. On the other hand, if a more aggressive tourism industry develops, the added income and employment due to the proposed lakeshore could be more than twice the above projections, or $6,242,700 and 365 jobs, respectively. Both of these projections include an estimated $166,700 spent for 27 full-time job-equivalents for operating and maintaining the proposed lakeshore. These projections extend ten years into the future.

The lower of the two estimates is based upon an estimate of 500,000 annual visitors to the lakeshore, should it have been in full operation in 1962. Since the actual projection is for ten years later, the 500,000 is increased by 50 percent to 750,000 as an estimate of growth that may occur in a decade. There are a number of good indices for such estimates: (1) Crossings of the St. Mary’s River at Sault Ste. Marie increased by 160,000 between 1960 and 1961 when the Canadian North Shore Route was opened; (2) The Cape Hatteras National Seashore had an attendance of 649,000 in 1962. (3) Attendance at the Porcupine Mountains State Park is approximately 200,000 (it has only one overlook). (4) A number of specific attractions in the Upper Peninsula have had rapid growth in visitation despite recent stagnation in the general tourism industry of the region. (5) Elements of the National Park System that are resource-based have been experiencing an annual increase in the use of 9 to 12 percent, thus, a 50 percent increase in ten years appears reasonable in a passive setting.

Taxation

Removal of all privately owned land in the “recreation zone” from tax rolls would reduce the combined incomes to Munising Township, Munising City, and Burt Township by about $12,400. This is made of property tax revenues plus a $771 payment from the State of Michigan in lieu of taxes on state-owned lands.

A partial immediate compensation for this tax income reduction will result from park development work. Preliminary plans program an expenditure of $5,826,950 for this purpose over a four-year period. If even the lowest estimate of added employment due to the lakeshore is realized, personal property taxes of employees alone would account for more than tax losses. Property value improvement due to expanded business should add even more tax revenues.

NOTE: In 1962 there were only 164 structures in the proposed lakeshore. While buildings are distributed throughout the area, most intensive developments are on Miners Beach, Grand Sable Lake, and in and near Munising City.

Economic Opportunities

Implementation of the proposed lakeshore would expand economic opportunities for private entrepreneurs. This increase will be in the tourism industry. Firms and individuals with land holdings in the vicinity may have especially favorable opportunities for business profit.

Forest industries will suffer a reduction in the form of fewer job opportunities in logging operations and accelerated pressures that have already caused the closing of many smaller mills. This loss will be offset by increases in tourist revenue and related job opportunities. Most of the firms owning large tracts of land for forestry purposes that are in the “recreation zone,” also have other holdings outside the proposed lakeshore. They are, thus, in one of the better positions to take advantage of new business opportunities that would develop; they have access to land, to financing and to top-level management — all of these are ingredients badly needed by the region’s tourism industry.

General Conclusions

Evidence of this study suggests a definite advantage to the economy of Alger County and the Upper Peninsula in the establishment of the proposed Pictured Rocks National Lakeshore. This advantage would come through improved opportunities in the tourism industry. Local logging and milling operations would be curtailed but this loss would be much more than offset. In addition, it is expected that no important reduction in the region’s ability to attract wood processing industries would occur.