MONTHLY WEATHER REVIEW 366 AUQUST, 1995
more than 1 inch per each 100 feet. Because of the elevation and winter precipitation most of the water fell in the form of snow, and glaciers were developed. This robbing of the winds of their mois- ture by the Coast and Cascade Ranges dried up the lakes of eastern Oregon. Glaciers developed in this manner would not result in
a reduction in the average temperature of western Oregon. On the contrary, these winds would contribute to Oregon the heat which they obtained from the warm Pacific. The moisture condensing to clouds and the cloud particles crystallizing to snow would cause these winds to give up their heat as a direct contribution to Oregon. The temperature undoubtedly was higher rather than lower. The above explanation involves no change in world climate, nor chang~ in direction of wind, nor change in inoisture content of the winds. In the Puyallup epoch there was a subsidence of over 1,000 feet, which reduced the mountain crests to one lower than that of the present time. The moist westerly winds again were able to pass over western Oregon retaining much of their moisture which was precipitated in eastern Oregon, .producing large lakes. In the Vashon epoch elevation again took place, resulting in
a second period of glaciation and the drying up of the lakes in eastern Oregon. At the close of the Vashon epoch there has been
a subsidence resulting in the drowning of most of the river valleys of the Pacific Northwest. This subsidence, however, was riot equal to that of the Puyallup epoch and consequently no great lakes have been developed. Thus there were two uplifts and two glacial periods in Admiralty and Vashon time. Waters derived from their glaciers cut large valleys in western Oregon and on the flanks of the Cascades in eastern Oregon. There were two lake stages, one in pre-Admiralty and one in the Puyallup. The lakes of this second period have been drving up since that time. During the Puyallup period, and while t h i Admiralty glaciers were melting, aggradation on a large scale filled the Willamette Valley with sediments to an elevation of about 600 feet in the vicinity of Portland and about 150 feet in the vicinity of Eugene. Further evidence that the climate was warm and that no chilling bodies of water existed is shown by the entire absence of marine fossils and by the presence of fossils of plants and animals requir- ing a warm climate. In western Oregon many fossil remains of the mammoth, mastodon, giant sloth, camel, and horse have been found. Fossil remains of the walnut, oak, willow, and sequoia have been found. The sequoia is apparently the same as the living sequoia in California at the present time and the oak and walnut are closely related to living species. These creatures could not have lived in Oregon had the climate been cold and would have been driven out if the valley had been occupied by a great sound. The glacial debris found in the Willamette Valley represer.t ice- borne fragments which floated down the Willamette Valley while the valley was flooded by river waters in the Puyallup epoch. This interpretation of the geology makes i t possible for men to have migrated down the Pacific coast under favorable conditions and to have lived in the Willamette Valley during the glacial
period. Fossil remains of a race of men antecedent to the Indiana, which the white men found in this valley, have been found under conditions which would indicate that man was here during the Puyallup Epoch.
VARIABILITY OF PRECIPITATION IN THE STATE OF WASHINGTON
By M. B. SUMMERS
[Weather Bureau, Seattle, Wash.]
(A bstrart)
The average precipitation in the State of Washington for indi- vidual months has varied between a trace and about 400 per cent of the mean of 35 years of record. The greatest variance occurs in the summer months and the most frequent variance in the
region of the Cascades. In general, the greatest amount that has been received in any 12 consecutive months has been about double that of the driest similar period in the western division, and about
three times the driest period in the eastern division. A singular feature of the variability in the eastern division is the fact that the July rainfall is above 150 per cent of the mean in about one year in three, and less than 50 per cent of the mean in about one year in three. A rather rhythmic fluctuation in the precipitation curve is apparent from 1900 to 1907, with an average period of about 18
montlls.
FLOODS IN THE WILLAMETTE RIVER
By EDWARD LANSING WELLS
[U. S. Weather Bureau, Portland, Oreg.]
(Author's abstract)
This paper outlines problems connected with the forecasting of floods in the Willamette River. The drainage basin has an area of approximately 11,000 square miles, varying greatly in surface and exposure, rising from near sea level to more than 10,000 feet. The climate is mild and equsble, with precipitation ranging from 38 inches to more than 100 inches, and averaging about 66
inches. There are 13 important tributaries, and there is no stretoh of more than 50 miles without the entrance of one or more of these. Rating tables form the best basis for relating stages at succes- sive stations, but these are not available for all stations. The river changes character as it drops over the falls at Oregon City, becoming, in a sense, an arm of the sea. The difference between crest stages at Salem and Portland is greater in extreme floods than in ordinary floods, and is greater when the Columbia is low, but this relation is not constant. Rises often begin at Portland almost as soon as at upstream stations.
,
The precipitation is distinctly seasonal.
NOTES, ABSTRACTS, AND REVIEWS
EVAPORATION MEASUREMENTS IN THE SWISS ALPS
J. Maurer and Otto Lutschg in Meteorologische Zeitschrift for March, 1925, p. 111-114, summarize
gations were made in 1911-12, the results being published in Meteorologische Zeitschrift, 1911, no. 12, and 1913, no. 5. In the summer of 1915, with the physical and financial resources of the Swiss Federal Bureau of Wat,er Control at their service, intensive studies were begun. These were carried on at first with open circular vessels of sheet zinc (evaporation pans) of.30 and 50 cm. diameter and depth, respectively, supplemented by Livingston porous cup atmometers and glass vessels of 24 and 2s
cm. diameter and 8 cm. depth, in the up er Saas Valley
which data are plotted in Fi re 1, these data repre- sentin conditions in 1920. gaporation measurements
orological elements. Evaporation pan measureinen ts were carried out on Lake Mattmark, at about 2,100
meters above sea level, during the summew of 1915 and 1916. The summer of 1915 gave 24-hour evaporation
their results as attained thus P ar. Preliminary investi-
at the various altitudes indicated for t K e stations ior
were a 5 ways accompanied by observations of the nieto-
values rangin between 6.2 mm. and 2 mm., according
warm and entirely clear period with li ht north wind. In 1916 the July and August 24-hour v a f ues ranged from
1.G mm. and 3.4 mm. The principal series of observations was made at the Hopschensee, 2,017 ni. above sea level, west of the Siniplon Pass, between July 35 and October 23, 1921.
These were carried through by means of hydrometrical methods, taking account of the inflow and outflow and direct recipitation which affected the level of the lake.
and glass vessel determinations was made in the meadow directly on the lake shore, the corresponding meteorologi- cal observations being taken also. Table 1 for the Hopsdiensee summarizes evaporation from this lake b certain calendar goups of days without conditions. Table l a for the same lafe divides the data for the same total period into groups accorclin to weather type, a much more significant
to the weat i? er. The maximum value represents a
Coinci s ent with these, a series of porous cup atmometer
re ard to weatier 9
procedure. Ta Q le 2 summarizes the resulta obtained by
356 MONTHLY WEATHER REVIEW AUGUST, 1925
the various methods at the lake, evaporation being ex- pressed in millimeters and temperatures in degrees cen- tigrade. The results of other nieasurements carried out in the same region during the course of the work, are not summarized. Unfortunately there is nothing in the original test of t#he paper as printed to indicate the precise meaning of those column Ileaclings of Table 2
which rend : Open station, sheltered station, lake east, and lake west. Presuniably the first two refer to the topographic situation. The last two are, obviously, open to important differences of interpretation.
TABLE 1.-Means of witid islocity and water teniperaticre, totals of
precipitation, tola1 and naenti daily etlnporatioii, and maximum
a i d nririimiim daily eznporation, for &he Hopschensce, west of the siitninit of Siniplon Pass, at 8,017 I t ). above sea leuel, for foitr pcriods, .wmmer of 1921
~
I I I I
Month
J~ly25-Aug. 1 I i d a W --__ 2.9 19.0 0.4 29.0 4.1 I 4.5 3.1
Oct. 1-Oct. 23 (22 days) -___ 3.45 8.2 0.0 11.3 1.1) I 3.4 0.9 Aug. Sept. 1-Sept. I-Oct. 1 1 l3Oda~sI...l !31 days) ____ i; 1 %: 1 $:! 1
2.4 1.S I ~
7.7 3.7
1 tk
TABLE la.-The sanie data arranged i.)i periods accord,ing to ,weather tgpe
I. Dry period. July 25-Aug. 10 (16 days) __________ 2.9 11. Wet period. AUK. 10-
AUK. 25 (15 days) _____ 3.5 111. Damp period. Aug. 2trSept. 23 I89 days)- 2.8 IV. Dry period, Sept. 23- Oct. 23 (Mdays).---. 3.4
Whole period from July 2trOct. 23 ti10 days) ___________ 2 8
-
- I
17.3 3.1
120 143.6
122 63.9
9.9 0.0 --.
12.3 310.6
70. i
18. 1
53.5
50.0 -
1%. 3
4.41 7.7
1.2 2. 15
i
2 2 1 7.7
-
1. i
0. 2
0.35
0.9 -
a2
ho. 1.-Evaporation measurements at various altitudes In the Visp rrgion, LY means of the Livingston porous cup atmometer
1 Means of morning and evening observations.
* Beginning and ending at S a. m. This arrangement applies to all the periods.
TABLE 2.-Conaparison of evaporation mzasurenisiils, by niearis of porous cup atnionieler and glass uessels, iuifh those 071 the Hopschensee,
8 iiininer, 1521
[ Evaporation in niiu., tenipcrnturvs in "C.]
Glass vessels
Evaporation lroni thc lake Tenlperatures At.iuometrr
Open station I Shcltcrrd st:ition
-- -____ Month
Aug.i-Yept.i(3ids)'s)--- Sept.1-Oet. l(30davs) _____
July ZS-Aug, 1 I7 daysV ...
Oct. I-Oet. 23 (2 diys) ____
Whole perlod from July 25
to Oct.23 (Wdays) ______
Y.I. 6 4. 31 81. 3 0.9;
222.9 2.48 414.6
I See footnote 2 of Table 1.
The general conclusions from the vaporation studies so far carried out in the lofty Siniplon region are RS
follows: Eva oration from the high Alpine lakes is in
the Alps. In the case of the hi 1.1 altitude lakes evapor- ation is somewhat aided b t le reduced atmospheric
reatly outweighed by the effect of the lower temperatures. L0ca.l conditions may enter into the result as either a
general sma 8 er than that froni the lakes at the foot of
pressure, but the increasec pf effect from this cause is
positive or a ne ative effect. There must be taken into
perat.ure of t,he water: The greater or less esposure of the lake and of its bributary region to insolation and wind; the character of the inflow into the lake; the area of the lake surface and the depth of the lake; the content of the snow cover; and the character of the adjacent land surface.-B. di. 1'.
consideration a1 7 the factors which determine the tem-