parts of the rock, for it is greatly shattered, so that it would be impossible to take out a block of much size. Many of these broken layers are cracked in every direction into small angular fragments of only a few inches in any dimension. But these broken beds are only occasional. Others, and these are much more numerous, are not broken, though all are more or less tilted. As everywhere in this formation, there is great diversity in the character of the layers. Some are shaly, others thick bedded. Most is a dark and rather bright red. Near the high cliff at the entrance of Shelburne Bay there are layers of dark, gray shale, closely resembling the Olenellus shale at the Parker quarry in Georgia. Beginning as a low outcrop the rock increases in thickness, forming a ledge along which there is for the most part little or no shore and continuing around the high bluff, the south side of which is shown in Plate XLVII to form the northern side of Shelburne Bay for some distance, and a few rods before reaching Queen City Park it goes under a high bank of drift. The whole extent of this exposure is over a mile, probably a mile and a half.

As has been noticed, the red sandrock extends through the state in a north and south direction, but its width is nowhere more than a few, usually very few, miles. In this county it is succeeded on the

east by what, at least for the present, we consider as the Beekmantown. It is certain, as will be shown, that some of the siliceous limestone which is found east of the Cambrian is Beekmantown and it appears very probable that all of it is of that age.

The varied and numerous layers of red sandrock in Colchester have been fully described. Nowhere else do these show so finely, and in Burlington and South Burlington, while in places, as we have seen, this rock is finely shown in cliffs on the shore of the Lake for short spaces, as at Rock Point and Red Rocks, yet as a whole the formation is better shown in Colchester. And when it comes to fossils there is nowhere in the county where anything at all like some of the fossiliferous layers of Colchester can be found.

At the highest point shown in Plate XLVII, for which I am indebted to Professor Kemp, the rocks rise nearly a hundred feet above the water, and farther inland a short distance they are sixty feet higher, as at what is called "The Eastern Outlook" at Red Rocks Park. There is a dike not far below the first outcrop and farther down three more of considerable size, as is shown in that part of this paper which takes up the dikes of the county.

For several miles beyond Queen City Park the shore has no rock in place, but at the south end of Shelburne Bay there is a small outcrop about level with the surface, and this is the last seen of the sandrock on the shore of the Lake, all the rock south of this point being Ordovician, all members of which are found at one or another locality.

The non-fossiliferous character of most of the Cambrian rocks in this region has been mentioned and also the fact that, in some cases, the absence of fossils is apparent only since when the rock is weathered fossils hitherto unseen come into view. In some few layers of the sandrock fossils can be plainly seen at all times, as in Plate XLII, but more often they are scarcely visible or not at all until long weathering has oxidized the material and brought them into distinctness. This has been shown in the case of rocks of this age in Franklin County. Specimens from the Colchester beds have been studied by Dr. Walcott and he has very kindly identified the following species, all of which were found within a few miles from Burlington, but in the town of Colchester:

Ptychoparia adamsi, Billings; Ptychoparia arenosa, Bill.; Ptychoparia miser, Bill.; Ptychoparia miser, var.; Ptychoparia teucer, Bill.; Ptychoparia vulcanus, Bill.; Olenellus thompsoni, Hall; Protypus desiderata, Walcott; Microdiscus speciosusy; Nisusia festinata, Bill.; Scenella varians, Walc.; Stenotheca rugosa, Hall; Lingula gonvillensis, Walc.; Salterella pulchella, Bill.; Hyolithes communis; Cruziana, sp.; Planolites; Scolithus.

Several other forms occur, but they are not sufficiently plain for identification. There are also several kinds of tracks, worm borings, etc. In addition are what have been already mentioned as possible algæ.

Dr. Walcott, 19th Report, U. S. G. S., gives twenty-eight species from the Cambrian rocks of western Vermont. Several species should be added to these and, naturally, additions are continually likely to be discovered. These are grouped as follows: Sponge 1, Celenterates 2, Brachiopods 6, Lamellibranchs 1, Pteropods 2, Crustacea 2, Trilobites 11. In some of the layers markings which appear to be identical with those shown in Fig. 2, Plate LIX, 10th Report, U. S. G. S., have been found. According to Nathorst, these "Eophyton" markings or casts have been made by medusæ as they moved over the sea bottom. The figures referred to are of Swedish

specimens, and so far as I know, have not been reported from this country, but we certainly find close resemblance in some of our Vermont specimens. Several forms of "Planolites" similar to those figured by Walcott, Plate LXI, 10th Rep., U. S. G. S., are found in great abundance in some parts of the rocks near Burlington. These have already been mentioned as probable casts of algæ, but it is only fair to quote from Dr. Walcott in regard to this, though I cannot fully agree with his conclusion: "As far as known to me there are no true algæ found in the rocks of the Lower Cambrian, except, possibly, in New Brunswick. That such forms existed there can scarcely be any doubt, but after a careful study of all reported species, I think they can be referred to trails of mollusks with much more propriety than to algæ." 1. c. page 602.

As to Planolites congregatus, a common form in some of the sandrock beds, Dr. Walcott says: "This and the following species, P. virgatus, were referred to the algæ by Mr. Billings. The reference may be correct, but these forms impress me as being casts of worm borings and there is nothing in the specimens to indicate their vegetable origin. The form of cast is found in sandy, argillaceous deposits all through the sedimentary rocks." So far as some of our Vermont specimens are concerned, it appears to me quite difficult to imagine any sort of worms that would or could move in such fashion as to leave burrows of such shape as we find in these casts. Not here and there, but over broad areas, that is, fifty to a hundred square feet, these markings may be seen thickly covering the surface of the stone as it is exposed in the quarry.

One or two specimens like those shown in Plate LX of the 10th Report, though much larger, have been found at Malletts Bay in a drab sandstone. This and the form shown in Figure 5 of the same plate, which is more common, are more undoubtedly worm borings and perhaps also a singular specimen from the Champlain marble which Dr. Walcott has referred to Scolithus linearis. This is the only specimen we have found. It came from the marble at Malletts Bay. The tubes filled with white calcite are very evident in the red of the surrounding material. Allusion has been made above to the Cruziana found in several of the layers at Malletts Bay. These are well shown in Plates LXIV-LXVI, 10th Report. They are certainly most puzzling fossils. Dr. Walcott says of them: “A careful examination of a large series of specimens of the trails and burrows referred to Cruziana from a single layer of sandstone, leads