Box 3, Folder 6: Typewritten Letters, 1849-1851

-787-

1849.

Proceeding west to Columbus (Sec. 13 T. 10 R. 12) we come upon the lower limestone "Calciferous rock" which is seen in the bed of the Crawfish Creek at the mill; and this rock shows itself as far as Sec. 27 T. 11 R. 10, where a wall reveals the sandstone, being the first seen on our route from Milwaukee. Fragments of an Oolitic limestone, or limestone with scattered particles of sand, were found in this vicinity, precisely like the layer seen at Janesville above the sandstone.

From this point to the Wisconsin river at Dekorra we traveled on a region of Sandstone which is the upper portion of the Potsdam, or Lower Calciferous. It is soft, friable, easily crumbling into sand. Colors, red, yellow, or white, of various shades. Occasionally a tinge of green.

At Dekorra the cliffs are entirely sandstone, soft, white and yellow.

From Dekorra we went to Fort Winnebago, where the Fox and Wisconsin rivers come so near together and thence up the "Piney Road" in a N.W. direction about five miles. All the way on sandstone. From information obtained here, I inferred the existence of a trap dyke" about three miles north of our stopping place and accordingly set out early in the morning with a guide to find it. He led me about four miles to some very high and steep, rocky bluffs which proved on examination to be only sandstone.

Immediately west of this place is a large, level country through which a slough winds its way without current, except in times of great rains, or wet seasons. This flat is said to extend across from the Wisconsin to the north fork of the Neenah river, it may at one time have been the channel through which the water

-788-

1848. [1849].

passed from one river to the other. It appears to be but little elevated above the present level of the streams. A slight barrier below would send all the waters of the Wisconsin down the Neenah to Green Bay. The existence of high lands between this and Fort Winnebago on both sides of the Wisconsin indicates that this barrier did formerly exist.

We arrived at Dell creek, near the foot of the Dells, just at night; but were much struck with the difference in the character of the sandstone here, from that observed further east. It undoubtedly belongs to the lower or older portion of the formation, being the true Potsdam Sandstone of the N.Y. geologists and the Inferior Sandstone of Mr. Foster. The rock has a greater hardness and a somewhat regular stratification; the different degrees of hardness and consequent power to resist the action of the elements has given rise to many fantastic shapes in the cliffs. At the place where the ferry boat leaves the shore, on the east side of the river we first observed the layer of diagonal and curved strata which is so conspicuous a figure above. It is here about three feet thick, but gradually becomes thicker as we ascend the river from this place (Sec. 15 T. 13 R.6).

The next morning our eagerness to see the "dreadful Dells" induced us to leave our beds at five o' clock and drive four miles to the "Dell House" (on Sec. 33 T. 14 R.6) situated at the foot of the steep rocky gorge. (Sketch).

The accompanying drawing is a section of the river at this point showing the arrangement of the strata including the curiously curved one. The river is now unusually low so that the current is not as rapid as usual.

-789-

1849.

In this respect we were very fortunate as we were able to find a man who was willing to paddle us up through the gorge in a small boat. When the water is high (about 15 feet above its present level) the narrowness of the passage causes it to rise and rush through with great force and velocity. At such times it would be impossible to ascend with a boat. The constant flow of the water has worn away the rocks on each side so that the river is wider at the water level than a little higher up. The width of the gorge in the narrowest place is about fifty feet, so that the story recorded on some old maps that one could jump across it, is without foundation in truth. At this place a bridge is contemplated for which a charter has been granted by the Legislature of the State. The general width may be stated at from 50 to 100 feet.

It is related that a stick of timber 32 feet long was slid down the hill and precipitated over the bluff endwise into the water; that it went down and remained for some time out of sight, such is the great depth of water. It may be supposed to be fifty feet deep.

The Dells may be considered as extending from near the mouth of the Lemonweir, ten miles above the "Dell House" to the mouth of Dell Creek, four miles below, having therefore a length of about fourteen miles. Lost of the way the gorge is not so narrow as at the point visited by us.

As we paddled along against the current we occasionally crossed from one side to the other to take a vantage of eddies and places where the water ran less swiftly. When passing some points of rock the force of three paddles was required to stem the rapid current. One guide at one place directed the boat into an opening in the cliff, just sufficiently large to admit us; we passed for

1849.

-790-

some yards through this side channel and again emerged from another opening above the first. At another point we entered a large fissure which extended 30 feet from the edge of the water. It gradually diminished in width above until it was nearly closed at the surface of the ground high above our heads. We noticed many other smaller fissures.

As we ascended along the margin of the river, we had a good view of the strata on the opposite side and we could observe that the curved layers gradually increased in thickness, through always placed between horizontal layers above and below. We soon came to where the curved strata were more irregular as represented in the drawing; resembling the banks of sand, gravel and clay in the "Drift." This is said to be also the character of the sandstone on Lake Superior, forming the Pictured Rocks.

No traces of fossils were discovered. The sand is uniformly fine grained and the particles rounded. They are held together without any apparent cement or admixture of other substance of any kind.

The navigation of the Dells is very difficult, requiring much skill and experience to guide the crafts of lumber &c.--through without striking against the numerous projecting points.

The vegetation about the Dells presents some peculiarities. We find here the white, yellow and scrub pine (P. strobus, P. resinosa and P. Banksiana), the hemlock and cedar &c., &c. Among the shrubs we noticed Comptonia asplenifolia, not before accredited to Wisconsin.

From the Dells we passed south over a prairie and oak [oak] opening to the little town of Lyons, situated on the Baraboo

1849.

-791-

river one mile above Adams, the county seat of Sauk county. About one mile north of Lyons (on Sec. 27 T. 12 R. 6) we found a ledge of rock precisely similar to that found at Portland in the S.W. corner of Dodge county. It has the same quartzey crystalline character and is evidently the same geological formation.

Looking about we found large fragments of conglomerate, apparently of the same kind of rock, the pebbles of various sizes but usually less than an inch in diameter. Upon further investigation we found the conglomerate in place forming part of the ledge; thus showing that this rock is not primitive, but only an altered sandstone and conglomerate: A little further towards the town we found the sandstone only partially changed by heat--thus rending the conclusion evident that this Dodge county granite is only a metamorphosed sandstone, a sandstone modified and changed by heat. This heat must have been but moderate, not being sufficient to melt the sand and convert it into "trap rock." It must have had also but a limited extent, for it is but a short distance to where the sandstone remains unaltered. This explains also why the limestone near Portland remains unchanged only a short distance from the granite.

Portions of the partially altered sandstone, near Lyons, is everywhere penetrated by small cylindrical cavities (Scolithus lineatus, Hall Pal. 1., p. 2, Pl. 1 fig. 1) partially filled with ferruginous matter. They may be the remains of some fossil, but this cannot be very well made out.

A mile below Adams the sandstone is quarried in the high bluffs. Here are numerous fragments of limestone, indicating the former existence of that rock above the sandstone at no great