by Tom Gurney
Tom Gurney BSc (Hons) is an art history expert with over 20 years experience
Published on June 19, 2020 / Updated on October 27, 2026
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Mosquito Trail, Rocky Mountains of Colorado: Introduction
Thomas Moran's Mosquito Trail, Rocky Mountains of Colorado places a small traveller and an animal on a dark ridge above an extensive mountain landscape. The National Gallery of Art's 1997 exhibition catalogue identifies the original as a watercolour dated 1875, in a private collection. Its modest size makes the breadth of the view particularly striking. [1]
The composition contrasts rough, nearby ground with pale snow and a succession of distant peaks. Human movement occupies only a small part of that space. The trail becomes a way to imagine passing through the landscape, while the picture itself offers a much broader experience of its distances.
At a Glance
- ArtistThomas Moran
- TitleMosquito Trail, Rocky Mountains of Colorado
- Date1875 in the 1997 National Gallery exhibition catalogue
- MediumWatercolour
- Dimensions24.8 × 36.2 cm in that catalogue
- CollectionPrivate collection, as catalogued in 1997
- Catalogue number51
- Image-record discrepancyThe Commons reproduction is labelled 1874
- Publication contextPrang's western portfolio, issued 1876
- Figure identityNot securely identified
Where this work sits in Moran’s career
The Chasm of the Colorado
1873–1874; completed in 1874A View of Venice
1891Point Lobos, Monterey, California
1912, signed and datedMosquito Trail, Rocky Mountains of Colorado
1875 in the 1997 National Gallery exhibition catalogueContents
- A ridge close to the spectator
- The traveller and the animal
- The pale mountain on the right
- The darker left-hand wall
- A succession of summits
- The original and the date discrepancy
- Colorado travel and the published trail
- Beside the Sierra paper work
A ridge close to the spectator
The foreground consists of fractured rock with numerous changes of direction. Some broad surfaces are pale; others fall into much darker tones. Narrow cracks and projecting edges interrupt the ground. The viewer encounters this rough surface before reaching the open mountain view beyond it.
Dark rocks rise towards the left and middle, forming a low, irregular crest. Their silhouettes stand against the much lighter valley. This makes the ridge easier to follow across the picture. It also gives the foreground a strong presence without allowing it to hide most of the distant landscape.
The right-hand part of the ridge slopes down towards the edge. Its darker band carries the small traveller and animal. The line does not behave like a wide, smoothly engineered road. It remains part of the uneven ground, close to surfaces that suggest difficulty underfoot.
The spectator's position is therefore both elevated and physically constrained. We can see a great distance, but the near terrain is full of obstacles. The contrast makes the view feel discovered through effort. Its breadth is available to the eye even where easy movement through the landscape is less obvious.
Annotated Details from Mosquito Trail, Rocky Mountains of Colorado
Compare these details with the full composition. The numbered overview and crops come from the same original image.
Details from MOSQUITO TRAIL, ROCKY MOUNTAINS OF COLORADO
Open a detail to see it more closely.
A ridge close to the spectator
The foreground consists of fractured rock with numerous changes of direction. Some broad surfaces are pale; others fall into much darker tones. Narrow cracks and projecting edges interrupt the ground. The viewer encounters this rough surface before reaching the open mountain view beyond it.
The traveller and the animal
The figures appear towards the right of centre, where the foreground ridge is silhouetted against pale snow. Their placement makes them readable without increasing their size. A small dark mark can carry considerable significance when its immediate surroundings are sufficiently light.
The pale mountain on the right
A substantial snow-covered form rises on the right. Its upper outline is clearer than some of its lower passages, where pale surfaces merge into the surrounding valley. Lines of darker exposed rock interrupt the snow. These divisions make the mountain appear structured rather than uniformly white.
The darker left-hand wall
The mountain wall on the left is steeper in appearance and more strongly divided into vertical passages. Its darker surface contrasts with the smoother spread of snow opposite. The difference makes the central valley feel enclosed by unlike forms rather than repeated mountain shapes.
The traveller and the animal
The figures appear towards the right of centre, where the foreground ridge is silhouetted against pale snow. Their placement makes them readable without increasing their size. A small dark mark can carry considerable significance when its immediate surroundings are sufficiently light.
The traveller appears to move beside the animal, with a line connecting the two. Their arrangement creates a short sequence across the ridge. It introduces direction and activity into a landscape otherwise dominated by large, comparatively still forms. The picture gains a possible passage through its foreground.
Neither figure is large enough to become a detailed portrait. The traveller's identity should not be assumed to be Moran's own, and the image does not supply a securely documented personal narrative. The figures matter primarily through their relationship with the terrain and with one another.
They also help establish scale. The near rocks become large beside them, while the snowy slopes extend far beyond their small group. The viewer can imagine the length and difficulty of a journey across such ground. The painting makes human presence legible while keeping the surrounding mountains dominant.
The pale mountain on the right
A substantial snow-covered form rises on the right. Its upper outline is clearer than some of its lower passages, where pale surfaces merge into the surrounding valley. Lines of darker exposed rock interrupt the snow. These divisions make the mountain appear structured rather than uniformly white.
The broad slopes contain changes of direction that the eye can follow from summit towards valley. Some lines descend more steeply; others spread sideways. Their interplay gives the mountain a varied surface. The snow covers and reveals its form at the same time, depending on the passage being examined.
Near the base, small upright marks indicate sparse trees. They introduce a different kind of texture into the pale ground. Because they are so much smaller than the nearer rocks and figures, they also suggest a further interval of distance. The landscape includes several scales within a relatively small image.
The mountain's position creates an important counterweight to the darker left side. It has visual weight through breadth and brightness rather than through deep colour. The composition remains balanced because its two sides attract attention in different ways. Dark rock and pale snow cooperate without becoming symmetrical.
The darker left-hand wall
The mountain wall on the left is steeper in appearance and more strongly divided into vertical passages. Its darker surface contrasts with the smoother spread of snow opposite. The difference makes the central valley feel enclosed by unlike forms rather than repeated mountain shapes.
Pale snow lies near the top and in irregular passages along the side. It breaks the dark mass into smaller relationships of light and shadow. Some surfaces seem exposed, while others appear partly covered. The eye can read the wall as substantial without being able to assign every division to a named geological feature.
The lower part turns towards the central basin. Its slopes lead attention downwards and inwards, helping connect the higher mountains with the smaller dark body of water below. The landscape's structure becomes easier to understand through these movements. A high wall can also act as a guide towards depth.
The water is a comparatively small dark interval within a much lighter area. It introduces a quieter surface between the mountain masses. Its exact shoreline is not equally clear throughout the reproduction, but its placement helps organise the valley. The eye finds a stopping place before moving further towards the distant peaks.
A succession of summits
Beyond the main valley, jagged peaks cross the middle and upper distance. They overlap rather than presenting one uninterrupted line. Some stand against light sky; others are partly absorbed into the surrounding atmosphere. The changes in clarity suggest a landscape extending beyond the nearest mountain walls.
The sky occupies less of the composition than the mountains and foreground combined. Light clouds sit close to the peaks, making the boundary between land and atmosphere active. Several forms seem to emerge from a surrounding brightness. Their remoteness is conveyed by changing contrast as much as by their smaller size.
The foreground ridge is much firmer in outline. That distinction allows the eye to move from emphatic nearby shapes to more uncertain distant ones. The composition gives us a place to stand, then gradually loosens its description. Distance is experienced through successive degrees of clarity.
The available reproduction has a cool overall colour balance. Other reproductions can differ, so a digital image should not be treated as a precise record of the original pigments or current condition. The relationships of dark ridge, pale snow and overlapping peaks remain the clearest basis for close comparison.
Watch: Thomas Moran
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The painting that inspired a National Park
A close discussion of Moran’s landscape and its relationship to the idea of Yellowstone.
Watch on YouTubeThe original and the date discrepancy
The 1997 catalogue gives 1875 for the watercolour and reproduces this composition with its small traveller, animal and rocky foreground. The Wikimedia Commons file gives 1874. The two dates should be reported transparently, with the scholarly catalogue's date used for the original discussed here. [2]
The discrepancy does not justify inventing an undocumented sequence of separate versions. Nor should the image file's date be allowed to turn the watercolour into an oil painting. The catalogue identifies its medium, measurements and private-collection status. Those particulars establish the object more securely than a general label attached to an image.
The stated private collection belongs to the 1997 catalogue record. It should not be converted into a claim about a named current owner or present public display. The work remains accessible here through a separately cleared faithful reproduction, with the source and its different date label acknowledged.
Colorado travel and the published trail
Moran travelled through Colorado in 1874. The catalogue's chronology records mountain camps and his return east, providing context for the following year's watercolour. That broader journey does not identify the small foreground traveller or prove the date of every field study connected with this image. [1]
The letterpress accompanying Prang's western portfolio describes the Mosquito Trail as a miners' route across high mountain terrain. It associates the scene with passes above the timber line and with a powerful sense of remoteness. These are historical descriptions of the subject offered to the publication's readers.
The image gives that setting a human dimension. A route that could be described geographically becomes a narrow passage beneath a small moving group. The mountains retain their breadth while the trail supplies an imaginable activity. Its importance comes from the relationship between the traveller and the surrounding space.
Prang issued the portfolio in 1876, using specially prepared watercolours for its chromolithographs. The published colour print and the original watercolour belong to different stages of the image's circulation. Their connection does not make them the same physical object, and the portfolio text should not be read as present-day route guidance. [1]
Beside the Sierra paper work
Summit of the Sierras offers a useful comparison. The Art Institute identifies it as gouache over graphite on cream laid paper, dated 1872/75. Its upright format gives a nearer tree a major role, whereas the Mosquito Trail watercolour spreads its peaks and foreground ridge across a broader view. [3]
The two compositions place the viewer near rough ground while opening a much greater distance beyond it. Their different foregrounds change the experience. A tall tree makes the spectator look past an upright obstacle; a rocky ridge with a traveller invites an imagined movement across the picture.
The Mountain of the Holy Cross provides a further connection with Moran's Colorado subjects. Each work gives mountainous terrain a different centre of attention. In Mosquito Trail, the small journey and the extensive snowy setting remain inseparable. The view is grand, but its human scale is quietly carried by a few dark marks near the foreground crest.
Artworks directory
Selected documented works and distinct versions. This directory is not a comprehensive catalogue raisonné. Dates and media retain the distinctions explained in the articles and museum records.
| Name | Date | Medium |
|---|---|---|
| An Arizona Sunset near the Grand Canyon | Date not securely established | Oil painting |
| Autumn Afternoon, the Wissahickon by Thomas Moran | 1864 | Oil on canvas |
| Cascade Falls, Yosemite | Commonly catalogued as 1905 | Catalogued as oil on canvas |
| The Chasm of the Colorado | 1873–1874; completed in 1874 | Oil on canvas, currently mounted on aluminium |
| Children of the Mountain | 1866 in the current museum title; 1867 in the 1997 National Gallery catalogue | Oil on canvas |
| Cliffs of Green River | 1874 | Oil on canvas |
| Cliffs of the Upper Colorado River, Wyoming Territory | 1882 | Oil on canvas |
| East Hampton, Long Island , also captioned Easthampton, L.I | 1897 | Oil on canvas laid on board, according to the reproduction record |
| Fiercely the red sun descending, Burned his way along the heavens | 1875–76 | Oil on canvas |
| Forest Scene | 1870 | Oil on canvas |
| Grand Canyon of the Colorado River | 1892 and 1908 | Oil on canvas |
| Green River Cliffs, Wyoming | 1881 | Oil on canvas |
| Green River, Wyoming | 1878 | Oil on panel |
| The Juniata, Evening | 1864 | Oil on canvas |
| Mosquito Trail, Rocky Mountains of Colorado | 1875 in the 1997 National Gallery exhibition catalogue | Watercolour |
| Mountain of the Holy Cross | 1875 | Oil on canvas |
| The Much Resounding Sea | 1884 | Oil on canvas |
| Point Lobos, Monterey, California | 1912, signed and dated | Oil on canvas |
| Shoshone Falls on the Snake River | 1900 | Oil on canvas |
| Summit of the Sierras | 1872/75, as catalogued by the Art Institute of Chicago | Gouache over graphite on cream laid paper |
| The Teton Range | 1897 | Oil on canvas |
| The Three Tetons | 1895 | Oil on canvas |
| Tower Falls, Yellowstone | 1872 | Watercolour and gouache over graphite on blue laid paper |
| A View of Venice | 1891 | Oil on canvas |
| The Grand Canyon of the Yellowstone | 1872 | Oil on canvas, currently recorded as mounted on aluminium |
| Mountain of the Holy Cross, Colorado (etching) | 1888 | Etching, roulette and aquatint |
| The Resounding Sea (etching) | 1880 | Etching |
| The Much Resounding Sea (later etching) | 1886 in heading; 1888 on plate | Etching, drypoint and roulette |
| Tower Falls (Prang print) | c. 1875; portfolio issued 1876 | Chromolithograph |
| Shoshone Falls (early watercolour) | 1874 | Watercolour |
| Venice (watercolour) | 1888 | Watercolour over graphite |
Frequently Asked Questions
1875, following the National Gallery's 1997 exhibition catalogue. The Commons image record uses 1874.
The catalogue identifies it as watercolour.
24.8 × 36.2 cm in the 1997 catalogue.
The figure is not securely identified.
No. A chromolithograph is a separately produced printed object connected with the design.
Discussion
Cover the traveller and animal briefly, then look at the whole image again. How does their presence change the apparent size and accessibility of the mountains?
Reader Insights
Editorial prompts for close looking and discussion.
Cover the traveller and animal briefly, then look at the whole image again. How does their presence change the apparent size and accessibility of the mountains?
Which source or image helps you assess the interpretation?
How does this page compare with the related works linked above?
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References
- Nancy K. Anderson and contributors, Thomas Moran, 1997, catalogue no. 51, p. 104; selected 1874 chronology, p. 211; Prang publishing discussion, pp. 318–319; appendix transcription, “The Mosquito Trail”, p. 344.
- Wikimedia Commons, Thomas Moran Mosquito Trail, faithful-reproduction file record, date label and public-domain notice; composition compared with Anderson and contributors, catalogue no. 51.
- Art Institute of Chicago, Summit of the Sierras, authoritative object record, 1872/75, 1965.852.
- Splash image source.
The Mosquito Trail, Rocky Mountains of Colorado, watercolour, catalogued 1875 in the National Gallery of Art exhibition catalogue. Private collection; faithful reproduction via Wikimedia Commons. Image source. Public Domain Mark; faithful reproduction of a two-dimensional public-domain work. Resized only; complete source image retained.
- Splash image source.
The Mosquito Trail, Rocky Mountains of Colorado, watercolour, catalogued 1875 in the National Gallery of Art exhibition catalogue. Private collection; faithful reproduction via Wikimedia Commons. Image source. Public Domain Mark; faithful reproduction of a two-dimensional public-domain work. Numbered circles added to the overview; details cropped from the original reproduction. No colour adjustment or sharpening.
- Splash image source.
The Grand Canyon of the Yellowstone, 1872. Wuselig / Wikimedia Commons, CC BY-SA 4.0; U.S. Department of the Interior Museum painting. Image source. CC BY-SA 4.0; also marked PD-Art. Outer museum frame cropped; resized. Painted composition retained; photographic perspective unchanged. This image derivative is available under the same licence.
- Splash image source.
The Chasm of the Colorado, 1873–1874. U.S. Department of the Interior Museum; faithful reproduction via Smithsonian American Art Museum / Wikimedia Commons. Image source. Public Domain Mark; faithful two-dimensional reproduction. Resized only; complete source image retained.
- Splash image source.
Mountain of the Holy Cross, 1875. Autry Museum of the American West; faithful reproduction via Wikimedia Commons. Image source. Public Domain Mark; faithful two-dimensional reproduction. Resized only; complete source image retained.
- Splash image source.
Shoshone Falls on the Snake River, 1900. Wolfgang Sauber / Wikimedia Commons, CC BY-SA 3.0; Gilcrease Museum painting. Image source. CC BY-SA 3.0; also marked PD-Art. Resized only; complete source image retained. This image derivative is available under the same licence.
- Splash image source.
Green River Cliffs, Wyoming, 1881. National Gallery of Art, Gift of the Milligan and Thomson Families. Image source. Public domain; NGA Open Access. Resized only; complete source image retained.
- Splash image source.
A View of Venice, 1891. Smithsonian American Art Museum, Transfer from the U.S. Department of the Interior, National Park Service, 1968.120.1. Image source. Free to use; Smithsonian Open Access. Resized only; complete source image retained.
- Splash image source.
The Three Tetons, 1895. The White House Collection, Gift of C. R. Smith; faithful reproduction via Wikimedia Commons. Image source. Public Domain Mark; faithful reproduction of a two-dimensional public-domain work. Resized only; complete source image retained.
