Lindgren, the geologist, affirms that after the Sierra Nevada range was thrust up, high into the heavens, vast and long continued erosion "planed down this range to a surface of comparatively gentle topography." He claims that it must originally have been of great height. Traces of this eroded range (Cretaceous) "still remain in a number of flat-topped hills and ridges that rise above the later tertiary surface. There is reason to believe that this planed-down mountain range had a symmetrical structure, for somewhat to the east of the present divide is a well-marked old crest line extending from the Grizzly Peak Mountains on the north, in Plumas County, at least as far south as Pyramid Peak, in Eldorado County. At sometime in the later part of the Cretaceous period the first breaks took place, changing the structure of the range from symmetrical to monoclinal and outlining the present form of the Sierra Nevada."

This great disturbance he thinks, "was of a two-fold character, consisting of the lifting up of a large area including at least a part of the present Great Basin [Nevada and Utah] and a simultaneous breaking and settling of the higher portions of the arch. Along the eastern margin a system of fractures was thus outlined which toward the close of the Tertiary was to be still further emphasized. The main break probably extended from a point south of Mono Lake to Antelope Valley and from Markleeville northward toward Sierra Valley. A large part of the crust block to the west of this dislocation also sank down. This sunken area is now indicated by Lake Tahoe and by its northward continuation, Sierra Valley, separated from each other only by masses of Tertiary lavas.... It is worthy of note that within the area of the range no volcanic eruptions accompanied this subsidence."

He continues: "As a consequence of this uplift the erosive power of the streams was rejuvenated, the Cretaceous surface of gentle outline was dissected, and the rivers began to cut back behind the old divide, carrying their heads nearly to the present crest line that separates the slope of the Sierra from the depression of Lake Tahoe."

These rivers are the great gold bearing streams that caused the mining excitement of 1849. They all head near the Tahoe region, and include the Yuba, Feather, American, Mokelumne, Calaveras, Cataract, and Tuolumne.

Here, then, were two crest lines—the old Cretaceous line of which the Crystal Range immediately overlooking Desolation Valley on the west, with Pyramid and Agassiz Peaks as its salient points,—and the new Tertiary crest line, reaching somewhat irregularly from Honey Lake in the north to Mono Lake in the south. At the north of Lake Tahoe, "southwest of Reno, a large andesitic volcano poured forth lavas which extend between the Truckee River Canyon and the Washoe Valley. In the region extending northward from Lake Tahoe to Sierra Valley enormous andesitic eruptions took place, and the products of these volcanoes are now piled up as high mountains, among which Mount Pluto nearly attains 9000 feet."

These are the volcanic lavas which united the two crests forming the eastern and western borders of the Tahoe basin or depression, and through which the Truckee River had in some way to find passage ere it could discharge its waters into Pyramid Lake, resting in the bosom of the Great Basin.

Here, then, we have the crude Tahoe basin ready for the reception of water. This came from the snow and rainfall on its large and mountainous drainage area, a hundred greater and lesser streams directly and indirectly discharging their flow into its tremendous gulf.

It should not be forgotten, however, that while Mt. Pluto was being formed, other vast volcanic outpourings were taking place. Well back to the west of the Tahoe region great volcanoes poured out rhyolite, a massive rock of light gray to pink color and of fine grain, which shows small crystals of quartz and sandline in a streaky and glossy ground mass. On the summits nearer to Tahoe the volcanic outflows were of andesite, a rough and porous rock of dark gray to dark brown color. Lindgren says: "By far the greater part of the andesite occurs in the form of a tuftaceous breccia in numerous superimposed flows. These breccias must have issued from fissures near the summit of the range and were, either before their eruption or at the time of issue, mixed with enormous quantities of water, forming mud flows sufficiently fluid to spread down the slope for distances of fifty or sixty miles. The derivation of the water and the exact mode of eruption are difficult to determine.... Towards the summits the breccias gradually lose their stratified character and become more firmly cemented. Over large areas in the Truckee quadrangle the andesite masses consist of breccias containing numerous dykes and rocks of massive andesite....

Lindgren, the geologist, affirms that after the Sierra Nevada range was thrust up, high into the heavens, vast and long continued erosion "planed down this range to a surface of comparatively gentle topography." He claims that it must originally have been of great height. Traces of this eroded range (Cretaceous) "still remain in a number of flat-topped hills and ridges that rise above the later tertiary surface. There is reason to believe that this planed-down mountain range had a symmetrical structure, for somewhat to the east of the present divide is a well-marked old crest line extending from the Grizzly Peak Mountains on the north, in Plumas County, at least as far south as Pyramid Peak, in Eldorado County. At sometime in the later part of the Cretaceous period the first breaks took place, changing the structure of the range from symmetrical to monoclinal and outlining the present form of the Sierra Nevada."

This great disturbance he thinks, "was of a two-fold character, consisting of the lifting up of a large area including at least a part of the present Great Basin [Nevada and Utah] and a simultaneous breaking and settling of the higher portions of the arch. Along the eastern margin a system of fractures was thus outlined which toward the close of the Tertiary was to be still further emphasized. The main break probably extended from a point south of Mono Lake to Antelope Valley and from Markleeville northward toward Sierra Valley. A large part of the crust block to the west of this dislocation also sank down. This sunken area is now indicated by Lake Tahoe and by its northward continuation, Sierra Valley, separated from each other only by masses of Tertiary lavas.... It is worthy of note that within the area of the range no volcanic eruptions accompanied this subsidence."

He continues: "As a consequence of this uplift the erosive power of the streams was rejuvenated, the Cretaceous surface of gentle outline was dissected, and the rivers began to cut back behind the old divide, carrying their heads nearly to the present crest line that separates the slope of the Sierra from the depression of Lake Tahoe."

These rivers are the great gold bearing streams that caused the mining excitement of 1849. They all head near the Tahoe region, and include the Yuba, Feather, American, Mokelumne, Calaveras, Cataract, and Tuolumne.

Here, then, were two crest lines—the old Cretaceous line of which the Crystal Range immediately overlooking Desolation Valley on the west, with Pyramid and Agassiz Peaks as its salient points,—and the new Tertiary crest line, reaching somewhat irregularly from Honey Lake in the north to Mono Lake in the south. At the north of Lake Tahoe, "southwest of Reno, a large andesitic volcano poured forth lavas which extend between the Truckee River Canyon and the Washoe Valley. In the region extending northward from Lake Tahoe to Sierra Valley enormous andesitic eruptions took place, and the products of these volcanoes are now piled up as high mountains, among which Mount Pluto nearly attains 9000 feet."

These are the volcanic lavas which united the two crests forming the eastern and western borders of the Tahoe basin or depression, and through which the Truckee River had in some way to find passage ere it could discharge its waters into Pyramid Lake, resting in the bosom of the Great Basin.

Here, then, we have the crude Tahoe basin ready for the reception of water. This came from the snow and rainfall on its large and mountainous drainage area, a hundred greater and lesser streams directly and indirectly discharging their flow into its tremendous gulf.

It should not be forgotten, however, that while Mt. Pluto was being formed, other vast volcanic outpourings were taking place. Well back to the west of the Tahoe region great volcanoes poured out rhyolite, a massive rock of light gray to pink color and of fine grain, which shows small crystals of quartz and sandline in a streaky and glossy ground mass. On the summits nearer to Tahoe the volcanic outflows were of andesite, a rough and porous rock of dark gray to dark brown color. Lindgren says: "By far the greater part of the andesite occurs in the form of a tuftaceous breccia in numerous superimposed flows. These breccias must have issued from fissures near the summit of the range and were, either before their eruption or at the time of issue, mixed with enormous quantities of water, forming mud flows sufficiently fluid to spread down the slope for distances of fifty or sixty miles. The derivation of the water and the exact mode of eruption are difficult to determine.... Towards the summits the breccias gradually lose their stratified character and become more firmly cemented. Over large areas in the Truckee quadrangle the andesite masses consist of breccias containing numerous dykes and rocks of massive andesite....

Lindgren, the geologist, affirms that after the Sierra Nevada range was thrust up, high into the heavens, vast and long continued erosion "planed down this range to a surface of comparatively gentle topography." He claims that it must originally have been of great height. Traces of this eroded range (Cretaceous) "still remain in a number of flat-topped hills and ridges that rise above the later tertiary surface. There is reason to believe that this planed-down mountain range had a symmetrical structure, for somewhat to the east of the present divide is a well-marked old crest line extending from the Grizzly Peak Mountains on the north, in Plumas County, at least as far south as Pyramid Peak, in Eldorado County. At sometime in the later part of the Cretaceous period the first breaks took place, changing the structure of the range from symmetrical to monoclinal and outlining the present form of the Sierra Nevada."

This great disturbance he thinks, "was of a two-fold character, consisting of the lifting up of a large area including at least a part of the present Great Basin [Nevada and Utah] and a simultaneous breaking and settling of the higher portions of the arch. Along the eastern margin a system of fractures was thus outlined which toward the close of the Tertiary was to be still further emphasized. The main break probably extended from a point south of Mono Lake to Antelope Valley and from Markleeville northward toward Sierra Valley. A large part of the crust block to the west of this dislocation also sank down. This sunken area is now indicated by Lake Tahoe and by its northward continuation, Sierra Valley, separated from each other only by masses of Tertiary lavas.... It is worthy of note that within the area of the range no volcanic eruptions accompanied this subsidence."

He continues: "As a consequence of this uplift the erosive power of the streams was rejuvenated, the Cretaceous surface of gentle outline was dissected, and the rivers began to cut back behind the old divide, carrying their heads nearly to the present crest line that separates the slope of the Sierra from the depression of Lake Tahoe."

These rivers are the great gold bearing streams that caused the mining excitement of 1849. They all head near the Tahoe region, and include the Yuba, Feather, American, Mokelumne, Calaveras, Cataract, and Tuolumne.

Here, then, were two crest lines—the old Cretaceous line of which the Crystal Range immediately overlooking Desolation Valley on the west, with Pyramid and Agassiz Peaks as its salient points,—and the new Tertiary crest line, reaching somewhat irregularly from Honey Lake in the north to Mono Lake in the south. At the north of Lake Tahoe, "southwest of Reno, a large andesitic volcano poured forth lavas which extend between the Truckee River Canyon and the Washoe Valley. In the region extending northward from Lake Tahoe to Sierra Valley enormous andesitic eruptions took place, and the products of these volcanoes are now piled up as high mountains, among which Mount Pluto nearly attains 9000 feet."

These are the volcanic lavas which united the two crests forming the eastern and western borders of the Tahoe basin or depression, and through which the Truckee River had in some way to find passage ere it could discharge its waters into Pyramid Lake, resting in the bosom of the Great Basin.

Here, then, we have the crude Tahoe basin ready for the reception of water. This came from the snow and rainfall on its large and mountainous drainage area, a hundred greater and lesser streams directly and indirectly discharging their flow into its tremendous gulf.

It should not be forgotten, however, that while Mt. Pluto was being formed, other vast volcanic outpourings were taking place. Well back to the west of the Tahoe region great volcanoes poured out rhyolite, a massive rock of light gray to pink color and of fine grain, which shows small crystals of quartz and sandline in a streaky and glossy ground mass. On the summits nearer to Tahoe the volcanic outflows were of andesite, a rough and porous rock of dark gray to dark brown color. Lindgren says: "By far the greater part of the andesite occurs in the form of a tuftaceous breccia in numerous superimposed flows. These breccias must have issued from fissures near the summit of the range and were, either before their eruption or at the time of issue, mixed with enormous quantities of water, forming mud flows sufficiently fluid to spread down the slope for distances of fifty or sixty miles. The derivation of the water and the exact mode of eruption are difficult to determine.... Towards the summits the breccias gradually lose their stratified character and become more firmly cemented. Over large areas in the Truckee quadrangle the andesite masses consist of breccias containing numerous dykes and rocks of massive andesite....

Lindgren, the geologist, affirms that after the Sierra Nevada range was thrust up, high into the heavens, vast and long continued erosion "planed down this range to a surface of comparatively gentle topography." He claims that it must originally have been of great height. Traces of this eroded range (Cretaceous) "still remain in a number of flat-topped hills and ridges that rise above the later tertiary surface. There is reason to believe that this planed-down mountain range had a symmetrical structure, for somewhat to the east of the present divide is a well-marked old crest line extending from the Grizzly Peak Mountains on the north, in Plumas County, at least as far south as Pyramid Peak, in Eldorado County. At sometime in the later part of the Cretaceous period the first breaks took place, changing the structure of the range from symmetrical to monoclinal and outlining the present form of the Sierra Nevada."

This great disturbance he thinks, "was of a two-fold character, consisting of the lifting up of a large area including at least a part of the present Great Basin [Nevada and Utah] and a simultaneous breaking and settling of the higher portions of the arch. Along the eastern margin a system of fractures was thus outlined which toward the close of the Tertiary was to be still further emphasized. The main break probably extended from a point south of Mono Lake to Antelope Valley and from Markleeville northward toward Sierra Valley. A large part of the crust block to the west of this dislocation also sank down. This sunken area is now indicated by Lake Tahoe and by its northward continuation, Sierra Valley, separated from each other only by masses of Tertiary lavas.... It is worthy of note that within the area of the range no volcanic eruptions accompanied this subsidence."

He continues: "As a consequence of this uplift the erosive power of the streams was rejuvenated, the Cretaceous surface of gentle outline was dissected, and the rivers began to cut back behind the old divide, carrying their heads nearly to the present crest line that separates the slope of the Sierra from the depression of Lake Tahoe."

These rivers are the great gold bearing streams that caused the mining excitement of 1849. They all head near the Tahoe region, and include the Yuba, Feather, American, Mokelumne, Calaveras, Cataract, and Tuolumne.

Here, then, were two crest lines—the old Cretaceous line of which the Crystal Range immediately overlooking Desolation Valley on the west, with Pyramid and Agassiz Peaks as its salient points,—and the new Tertiary crest line, reaching somewhat irregularly from Honey Lake in the north to Mono Lake in the south. At the north of Lake Tahoe, "southwest of Reno, a large andesitic volcano poured forth lavas which extend between the Truckee River Canyon and the Washoe Valley. In the region extending northward from Lake Tahoe to Sierra Valley enormous andesitic eruptions took place, and the products of these volcanoes are now piled up as high mountains, among which Mount Pluto nearly attains 9000 feet."

These are the volcanic lavas which united the two crests forming the eastern and western borders of the Tahoe basin or depression, and through which the Truckee River had in some way to find passage ere it could discharge its waters into Pyramid Lake, resting in the bosom of the Great Basin.

Here, then, we have the crude Tahoe basin ready for the reception of water. This came from the snow and rainfall on its large and mountainous drainage area, a hundred greater and lesser streams directly and indirectly discharging their flow into its tremendous gulf.

It should not be forgotten, however, that while Mt. Pluto was being formed, other vast volcanic outpourings were taking place. Well back to the west of the Tahoe region great volcanoes poured out rhyolite, a massive rock of light gray to pink color and of fine grain, which shows small crystals of quartz and sandline in a streaky and glossy ground mass. On the summits nearer to Tahoe the volcanic outflows were of andesite, a rough and porous rock of dark gray to dark brown color. Lindgren says: "By far the greater part of the andesite occurs in the form of a tuftaceous breccia in numerous superimposed flows. These breccias must have issued from fissures near the summit of the range and were, either before their eruption or at the time of issue, mixed with enormous quantities of water, forming mud flows sufficiently fluid to spread down the slope for distances of fifty or sixty miles. The derivation of the water and the exact mode of eruption are difficult to determine.... Towards the summits the breccias gradually lose their stratified character and become more firmly cemented. Over large areas in the Truckee quadrangle the andesite masses consist of breccias containing numerous dykes and rocks of massive andesite....

Lindgren, the geologist, affirms that after the Sierra Nevada range was thrust up, high into the heavens, vast and long continued erosion "planed down this range to a surface of comparatively gentle topography." He claims that it must originally have been of great height. Traces of this eroded range (Cretaceous) "still remain in a number of flat-topped hills and ridges that rise above the later tertiary surface. There is reason to believe that this planed-down mountain range had a symmetrical structure, for somewhat to the east of the present divide is a well-marked old crest line extending from the Grizzly Peak Mountains on the north, in Plumas County, at least as far south as Pyramid Peak, in Eldorado County. At sometime in the later part of the Cretaceous period the first breaks took place, changing the structure of the range from symmetrical to monoclinal and outlining the present form of the Sierra Nevada."

This great disturbance he thinks, "was of a two-fold character, consisting of the lifting up of a large area including at least a part of the present Great Basin [Nevada and Utah] and a simultaneous breaking and settling of the higher portions of the arch. Along the eastern margin a system of fractures was thus outlined which toward the close of the Tertiary was to be still further emphasized. The main break probably extended from a point south of Mono Lake to Antelope Valley and from Markleeville northward toward Sierra Valley. A large part of the crust block to the west of this dislocation also sank down. This sunken area is now indicated by Lake Tahoe and by its northward continuation, Sierra Valley, separated from each other only by masses of Tertiary lavas.... It is worthy of note that within the area of the range no volcanic eruptions accompanied this subsidence."

He continues: "As a consequence of this uplift the erosive power of the streams was rejuvenated, the Cretaceous surface of gentle outline was dissected, and the rivers began to cut back behind the old divide, carrying their heads nearly to the present crest line that separates the slope of the Sierra from the depression of Lake Tahoe."

These rivers are the great gold bearing streams that caused the mining excitement of 1849. They all head near the Tahoe region, and include the Yuba, Feather, American, Mokelumne, Calaveras, Cataract, and Tuolumne.

Here, then, were two crest lines—the old Cretaceous line of which the Crystal Range immediately overlooking Desolation Valley on the west, with Pyramid and Agassiz Peaks as its salient points,—and the new Tertiary crest line, reaching somewhat irregularly from Honey Lake in the north to Mono Lake in the south. At the north of Lake Tahoe, "southwest of Reno, a large andesitic volcano poured forth lavas which extend between the Truckee River Canyon and the Washoe Valley. In the region extending northward from Lake Tahoe to Sierra Valley enormous andesitic eruptions took place, and the products of these volcanoes are now piled up as high mountains, among which Mount Pluto nearly attains 9000 feet."

These are the volcanic lavas which united the two crests forming the eastern and western borders of the Tahoe basin or depression, and through which the Truckee River had in some way to find passage ere it could discharge its waters into Pyramid Lake, resting in the bosom of the Great Basin.

Here, then, we have the crude Tahoe basin ready for the reception of water. This came from the snow and rainfall on its large and mountainous drainage area, a hundred greater and lesser streams directly and indirectly discharging their flow into its tremendous gulf.

It should not be forgotten, however, that while Mt. Pluto was being formed, other vast volcanic outpourings were taking place. Well back to the west of the Tahoe region great volcanoes poured out rhyolite, a massive rock of light gray to pink color and of fine grain, which shows small crystals of quartz and sandline in a streaky and glossy ground mass. On the summits nearer to Tahoe the volcanic outflows were of andesite, a rough and porous rock of dark gray to dark brown color. Lindgren says: "By far the greater part of the andesite occurs in the form of a tuftaceous breccia in numerous superimposed flows. These breccias must have issued from fissures near the summit of the range and were, either before their eruption or at the time of issue, mixed with enormous quantities of water, forming mud flows sufficiently fluid to spread down the slope for distances of fifty or sixty miles. The derivation of the water and the exact mode of eruption are difficult to determine.... Towards the summits the breccias gradually lose their stratified character and become more firmly cemented. Over large areas in the Truckee quadrangle the andesite masses consist of breccias containing numerous dykes and rocks of massive andesite....