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374
BANDS DO NOT CROSS MORAINES;
H
mi
nS'i
moraines, they could not be seen, the dirt on this part of
the glacier being sufficient to mask them.
The following interesting fact may perhaps have contributed to the production of the error referred to. Opposite
to Trelaporte the eastern arms of the dirt-bands run so
obliquely into the moraine of La Noire that the latter
appears to be a tangent to them. But this moraine runs
along the Mer de Glace, not far from its centre, and consequently the point of contact of each dirt-band with the
moraine moves more quickly than the point of contact of
the western arm of the same band with the side of the
valley. Hence there is a tendency to straighten the bands;
and at some distance down the glacier the effect of this is
seen in the bands abutting against the moraine of La Noire
at a larger angle than before. The branches thus abutting
have, I believe, been ideally prolonged across the moraines.
On the map published by Prof. Forbes in 1843 the
bands are shown crossing the medial moraines of the Mer de
Glace; and they are also thus drawn on the
map in Johnson's ' Physical Atlas' published in 1849. The text is also in accordance with the map:—"Opposite to
the Montanvert^'and beyond les Echelets,
the curved loops * (dirt-bands) extend
across the entire glacier. They, are single,
and therefore cut the medial 'moraine,
though at a very slight angle."—* Travels,'
p. 166. The italics here belong to Prof.
Forbes. In order to help future observers
to place this point beyond doubt, I annex,
in Fig. 38, a portion of the map of the
Fig. _8. jy^gj. ^g Q.iace taken from the Atlas re
ferred to. If it be compared with Fig. 35 the difference
between Prof. Forbes and myself will be clearly seen. The
portion of the glacier represented in both diagrams may
| Title | Tyndall, John, 1860, The Glaciers of the Alps. |
| Alternative Title | Glaciers of the Alps. |
| Creator | John Tyndall 1820-1893. |
| Subject |
Glaciers -- Alps. Alps -- Description and travel. Color. |
| Publisher | London : John Murray ... |
| DateOriginal | 1860 |
| Format | Tiff |
| Extent | 33 cm. |
| Identifier | col022 |
| Call Number | QE576.T914 1860 |
| Language | English |
| Relation | Color Science |
| Collection | Ice - 19th Century Polar Exploration & Glacial Studies |
| Rights | http://www.lindahall.org/imagerepro/ |
| Data Contributor | Linda Hall Library, LHL Digital Collections. |
| Title | Page 374. |
| Creator | John Tyndall 1820-1893. |
| Subject |
Glaciers -- Alps. Alps -- Description and travel. Color. |
| Publisher | London : John Murray ... |
| Format | tiff |
| Identifier | col022419 |
| Call Number | QE576.T914 1860 |
| Relation-Is part of | Is part of: The glaciers of the Alps : Being a narrative of excursions and ascents, an account of the origin and phenomena of glaciers, and an exposition of the physical princples to which they are related / By John Tyndall... |
| Relation | Color Science |
| Rights | http://www.lindahall.org/imagerepro/ |
| OCR Transcript | 374 BANDS DO NOT CROSS MORAINES; H mi nS'i moraines, they could not be seen, the dirt on this part of the glacier being sufficient to mask them. The following interesting fact may perhaps have contributed to the production of the error referred to. Opposite to Trelaporte the eastern arms of the dirt-bands run so obliquely into the moraine of La Noire that the latter appears to be a tangent to them. But this moraine runs along the Mer de Glace, not far from its centre, and consequently the point of contact of each dirt-band with the moraine moves more quickly than the point of contact of the western arm of the same band with the side of the valley. Hence there is a tendency to straighten the bands; and at some distance down the glacier the effect of this is seen in the bands abutting against the moraine of La Noire at a larger angle than before. The branches thus abutting have, I believe, been ideally prolonged across the moraines. On the map published by Prof. Forbes in 1843 the bands are shown crossing the medial moraines of the Mer de Glace; and they are also thus drawn on the map in Johnson's ' Physical Atlas' published in 1849. The text is also in accordance with the map:—"Opposite to the Montanvert^'and beyond les Echelets, the curved loops * (dirt-bands) extend across the entire glacier. They, are single, and therefore cut the medial 'moraine, though at a very slight angle."—* Travels,' p. 166. The italics here belong to Prof. Forbes. In order to help future observers to place this point beyond doubt, I annex, in Fig. 38, a portion of the map of the Fig. _8. jy^gj. ^g Q.iace taken from the Atlas re ferred to. If it be compared with Fig. 35 the difference between Prof. Forbes and myself will be clearly seen. The portion of the glacier represented in both diagrams may |
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