IOWA ACADEMY OF SCIENCE' 
13 
just above the “blueclay” issuing at times in springs of considerable 
volume. Such springs undermine the overlying deposits, cause constant 
slides of the loose material, so that in many cases, at least, the short 
ravines above mentioned are due to such causes and not to erosion by 
storm-water acting in the ordinary way. 
It must not be inferred that there is not erosion of the ordinary sort; 
there is plenty of it, of course; the most valuable agricultural lands 
of the whole district here considered are alluvial plains, filled up swamps 
and tide-flats; but the topography of the country is structural rather 
than erosional ; there are ravines and streams in plenty, but they follow 
old time ice-stream valleys, many of them the outflow of still existing 
glacial remnants clinging to the steeps of Mt. Rainier. 
However, this all may be, there are wide areas of comparatively level 
drift uncut by streams or at most by slow moving and insignificant 
waters that have not yet cut to base level. Besides there are many 
outw^ash terraces and plains. Every glacier-born river, the Nisqually 
for instance, is at this moment bringing from Mt. Rainier and spread- 
ing along a filling and widening channel, and especially in fan-shaped 
flats far down its course, vast quantities of water-rounded stones, 
pebbles, gravel, sand. Just such material, sometimes spread over many 
square miles forming considerable plains, occurs in different places all 
about the Sound, representing the deposition of far larger glacial floods 
in days not so very long gone by. A notable example is the famous 
lake region, the so-called “ prairie” south of Tacoma, a plain of water- 
worn material precisely like that now forming the bed of the Nisqually, 
the Steilacoom gravei. 
Upon the terrene thus so briefly sketched and under the meteorological 
conditions described, there stood until very recently one of the most 
remarkable forests of the world, associated with a wealth of non-arboreal 
species almost unrivalled in any area of equal size. Of flowering plants 
and ferns along there have been listed some 2,000 species, perhaps 25 
per cent more than are reported from the whole state of Iowa. In the 
entire state of Washington the students expect to list some day 4,000 
species of flowering plants. Such also is the variety of condition of 
soil, location, altitude, that plant-societies of every sort abound. We 
have a starving flora, consisting of but a few adventurous species near 
the very summit of Rainier, say 14,500 ft. A. T. ; we have the sedgy 
tide-flats, vast marshes covered with rushes and every sort of herbaceous 
green ; we have forest-shaded swamps crowded with skunk-cabbage and 
curious alders or maples knee-deep sometimes in water, and supporting 
tons of moss in various species, covering trunk and branch almost to 
