The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1870-10-20
A SUNKEN LAKE.
One Of the Natural Wonders of the Thuude

One of the Natural wonders of the Thunder
We extract the following from Prof. N. II.
Winchell's recent report on the Thunder Bay
REGION
Sunken Lake, in Sec. 80, T. SO, N. r. E,
is remarkable example of the effect of sub
terranean erosion. l have before described
the lake in full. Suffice it to say that the
North Branch of Thunder Bay River disap-
pears entirely in time of low water beneath
ledge of Hamilton limestone. But il time of
high water the mouth of the subterranean
channel will not admit the raised volume of
water, and after filing the basin of a little
lake, which is nearly mile in length it
passes overland through the channel repre-
sented as its bed on the maps During half
the year. however, this channel is one day
south of the lake.
During n recent trip up the Lake Huron
shore, north of Thunder Bay, it was one of
my objects to examine the reported outlet of
this river into Lake Huron. On the south
side, and near the head of the deep, crooked
bayou, tributary to Little Thunder Bay on
the north is a remarkably deep hole in the
o herNise shallow bed of the bay. The en-
trance of this long arm of Little Thunder
Bay is disguised by long, low island which
hangs across it. Any one in coasting would
be apt to miss it, as 1 did at first, unless he
followed carefully the same indentures of the
coast. Having entered the bayou, L directed
my man to follow the right bank, or north
side, and to return on the south sde Having
entered the bay, we began to coast outward
along the south shore. We had left the head
of the bayou, perhaps $50 rods, when there
was sudden increase in the depth of the
water. The weeds which had covered the
bottom entirely disappeared within space
no more than the length of the boat, and the
water was as black as at any place in the
open lake.
The motion the boat had attained carried
us over the chasm, and my pocket ther-
mometer told us the temperature of the water
was 67 deg. Fahrenheit. AS that was the
same as the temperature of the shoal water of
the bayou, observed few minutes before,
1 was disappointed, for 1 had expected to de-
tect the presence of river water, if it were
the outlet of Sunken Lake, by the difference
of temperature between the lake water and
that of the water rising from the opening.
Pushing the boat astern, we followed the rim
of the basin around towards the right and
found the descent very abrupt in all places.
The shoal water was filled with weeds, which
are common i'll inland lakes and slow and
flowing streams, and they were seen to cover
the brink and follow down the steep side as
far as the eye could distinguish. When the
boat reached the east side of the opening, the
weeds were seen to rapidly diminish, and they
soon entirely disappeared. The brink here
was very steep, almost perpendicular, and
consisted of sand, with considerable number
of fractured shells.
Our boat stopped upon the brink at this
place, and upon proceeding to make another
observation on the temperature of the water,
what was our surprise to find that we were
slowly drifting away from the opening. 1t
was fun ther observed that we we're in motion
against the breeze which was passing up the
bayou. I was again surprised to find that the
L
Fahrenbe This observation was made per-
haps ten feet to the east of the opening, and
as we were drifting, allowing the boat to
continue In motion, the tempera ure at thirty
feet from the opening was 60 degrees Fahren-
heit. The depth of the water at the place of
these last observations was not more than
eighteen twenty inches, and the bottom
was one of clean sand with frequent shells
common on the lake beach near the mouth of
rivers, but no weeds. Returning to the
opening and following the line of shoal
water in the same direction, we found that
the weeds soon became as abundant as on the
other side of the current. The current
ceased soon after we passed the most east
ward or lskeward side
The opening is six or eight rods across,
and nearly circular, and is nearest the south
side of the bayou, about twelve rods from
the shore. AS one passes over the brink and
loses sight of the weeds as they descend SO
quickly down the subaqueous brink, q feeling
of terror comes over the beholder, as if he
was about to be precipitated into an awful
cbasm. Fishermen report that a lead has
been lowered 800 feet into its opening with
out bottom. suppose the temperature of
the water over the opening is higher than
that of the current just east, because of the
influx OF the heated bayou water, and that
the real river water is found just over the
sandy part of the brink, and a little further
east. 1t was not until left the place that
remembered that the temperature of the
Thunder Bay river at Alpena, at two differ
eDt observations, was 30 deg. Fahrenheit.
In winter this is always free from ice, and
ducks frequent the place. 1 have no doubt
but this is the real outlet of the north branch
of Thunder Bay river, which disappears in