the evidence afforded by the fossils discovered by our survey at Quebec last summer year." Am. Jour. Sci., 3d Ser., Vol. 32, p. 232. After this there was little disagreement among geologists as to the primordial character of the Georgia formation. Nevertheless the question was not wholly settled for some years after this. Even as

late as 1868, Dr. T. S. Hunt, in a paper read at the Chicago meeting of the A. A. A. S., says:

"All the evidence, palæontological and stratigraphical, as yet brought forward, affords no proof of the existence in Vermont of any strata (a small spur of Laurentian excepted) lower than the Potsdam formation."

In Bulletin 30, U. S. Geol. Survey, to which somewhat extended reference has already been made, Dr. Walcott in 1886 placed the Georgia rocks in the Middle Cambrian, for we find throughout the article the fossils of the Georgia beds are referred to this period. As to the relations of these beds with the Potsdam, in which formation most geologists for some years placed these fossils, Dr. Walcott says, page 49:

"In the Georgia section, Vermont, one of the species, Ptychoparia adamsii, appears to pass up into the horizon of the 'lentile' of the section, where the fauna is more like that of the Potsdam. Of the other species, Orthisina orientalis is much like O. pepina of the Potsdam Sandstone of Wisconsin, but the fauna as a whole is so clearly distinct from the typical Potsdam of New York, Wisconsin, Tennessee, Alabama, Texas, Arizona, Nevada and Montana, that even without any section to show their relations with each other, I would not think of correlating them as possible faunas of the same geologic horizon."

Later, in giving a list of fossils limited to different Cambrian horizons, the Georgia species are given as Middle Cambrian, as is also the Georgia Group in a "Classification of North American Cambrian Rocks." In Bulletin 81 of U. S. Geol. Survey, CORRELATION PAPERS-CAMBRIAN, page 113, published in 1891, Dr. Walcott, after saying that during the summer of 1888 he visited Newfoundland and studied a section on Manuels Brook, Conception Bay, that "extends from the Archæan gneiss up to the Olenellus and Paradoxides zones," he goes on to say:

"In this unbroken section it was found that the Olenellus fauna occurred at the base and the Paradoxides fauna above. sitated a revision of the classification of the Cambrian.

This neces

The Lower

Cambrian with the Olenellus fauna is at the base, next the Middle Cambrian with the Paradoxides fauna, and lastly the Upper Cambrian or Potsdam zone, at the summit of which the Dikellocephalus fauna occurs. This correlation places the 'Red Sandrock' series, the Georgia shale and slate series, the 'Granular Quartz' and the 'Upper Taconic' of Emmons beneath the Middle Cambrian or Paradoxides zone of the Atlantic coast."

It is probable that typical Potsdam beds do not occur in large amount in Vermont. As has been seen in what has been said on preceding pages, formerly much of the rock of Franklin County was placed in this age, but more recent and complete examination of rocks and fossils has shown most of the former Potsdam to be Middle or Lower Cambrian, while some of the so-called Potsdam of the writers on Vermont geology of forty years ago is much more recent. Dr. Walcott writes in the Bulletin, 30, referred to already: "In the review of the references made to the 'Red Sandrock' series of Vermont frequent mention has been made of its correlation with the Potsdam Sandstone as well as of the correlation of the 'Granular Quartz' with the Potsdam Sandstone of the Adirondack area. As now known these two belong to distinct geological horizons, as claimed by Dr. Emmons in 1843. . . . The occurrence of the Upper Cambrian or Potsdam zone as distinct from the Georgia Slate and Red Sandrock, is spoken of in the description of the section crossing the town of Georgia, Vermont, where mention is made of the discovery of a fauna closely related to that of the Upper Cambrian."

As will be noticed in reading the foregoing account, all the Cambrian fossils found in Franklin County have been referred to the lower part of that age or Walcott's Olenellus zone. In the Intraformational Conglomerate mentioned by Mr. Edson in his article on the Geology of St. Albans, Fifth Report, page 143, there are well defined fossils which have puzzled us for some time. These are not at all abundant in the conglomerate, and when found are not easy to get out, but by diligent search Mr. Edson has succeeded in obtaining quite a collection. Dr. Walcott, during his work in the region also secured fossils from this part of the strata. Hitherto no study has been given to these fossils, but a short time ago I took selections of them to Dr. Walcott. On looking over the collections at Washington numerous specimens were found which had come from the same locality. Dr. Walcott gave them a preliminary examination and expected to furnish a list for this report, but has not been able

to do SO. He writes, as a investigation:

result of his brief preliminary

"The fauna is Middle Cambrian, as indicated by its general facies, and also by the presence of Paradoxides. Thirteen species are noted. One of the interesting occurrences is the presence of Paradoxides in the argillite. If this is the matrix of the conglomerate, it locates the horizon and also proves that the conglomerate is interformational."

While Dr. Walcott does not wish to commit himself as to the specific identification of these fossils, he sends the following list of genera:

Obolus, Lingulella, Hyolithes, Leperditia, Agnostus (two species), Agraulos, Menocephalus, Ptychoparia (three species), Anomocare, Paradoxides.

It appears very probable that many of the species are undescribed. The important point for the present, however, is the determination of the beds as Middle Cambrian, as no fossils of this period have heretofore been recognized in this state, although it has seemed almost certain that this part of the formation must be represented in our Vermont strata.

In closing this section of the Report, it may be well to explain that the reason for such liberal quotations as are found in the earlier pages is two-fold—that much of that quoted is not readily accessible to the people of this state, for whom the Report is primarily intended, and also because it must be a convenience to any student of Vermont geology to find the more important matter relating to this subject brought together from widely scattered sources.

Geology of the Town of Swanton.

BY GEORGE E. EDSON.

UTICA SHALE.

Commencing at the southern border of the town and passing northward along the shore of Lake Champlain, that is, along the western boundary, high cliff of Utica shale appear. They all dip towards the east. At this point, wherever the shale is seen it rises from the water, the only shore being that which is formed by pebbles of the same material, over which are strewn boulders of gneiss, sandstone and other rocks. Here as elsewhere in the Champlain Valley, the black shale is often crossed in every direction by veins of white calcite.

These conditions continue until the Hotel Champlain is approached and here the construction of a dock has changed the shore line. Northward from this place the shore is low, sandy and pebbly for about a mile, and on the land of O. M. Donaldson it is so low that when the water is unusually high it sets back over the low lands east of Maquam Bay. A small creek empties into the bay, running from the Mississquoi River on the north. By this West Swanton is made an island during some portion of the year.

The shore of the bay is three miles long and nowhere along its extent is any rock seen until near the house of E. S. Tabor, which is on the eastern part of the island, where the shore is covered by small water-worn pebbles derived from underlying shale. Going south by Bloody Point, we find the shore rising until it reaches the highest point on the island. This is near the southern end. South of this Bloody Point the shale forms a high bluff that extends into the lake.

The shore at the foot of this bluff is strewn with large boulders which lie on the upturned shale, since at this place the beds are tilted until almost vertical. Around this point and well up on the western side of the island the shale is still seen standing on edge, reaching to a height of twenty feet.

fossils are to be seen. North of this high bluff, the shore drops abruptly, a break occurs in the rock and the shore is little above water level, and the adjoining land inshore shows marks of yearly inundation. A small bay is seen here, but no rock and the low

Just across this part of the lake at Alburg the shale splits in large slabs, and upon their surface may sometimes be seen Triarthrus beckii in considerable number, but on this shore no such slabs nor