570 



SCIENCE. 



[Vol. I., No. 20. 



upon the wire. Therefore there is no good 

 reason to think that any thing would lia\'e been 

 gained at that time by the use of heavy 

 leads, though Mr. Ball thinks it strange that 

 they were not tried. In some of the trials a 

 twelve-pound lead was used, and, in the last 

 attempt, one of eight pounds, together with a 

 thermometer, with the usual result, — a break- 

 age of the wire. 



Mr. Ball's note implies that no successful 

 trials were made with the st^el wire ; but, ac- 

 cording to the xiubUshed log (p. 93, May 14, 

 18.50), at least one sounding was made (1,050 

 fathoms, no bottom) when the wire was suc- 

 cessfully recovered. A. E. Verrill. 



LAKE BONNEVILLE. 



Mr. G. K. Gilbert's report (Ann. rep. U. S. geol. 

 sun., 1881, 169), preliminary to the monoErrapli (in 

 preparation) he promises on the Great Basin, shows 

 the following history for its old lake. The lake- 

 deposits are chiefly a yellow clay of unknown depth, 

 covered hy a white marl ten to twenty feet thick, 

 the two being separated at certain points along the 

 old shore-lines by wedges of subaerial gravel-deposits, 

 and some exposures showing erosion of the clay sur- 

 face before the marl was laid on it. These deposits 

 mark two periods of high water, separated by a time 

 of low water, or dryness. As no cause is found in 

 the surrounding country to account for the change 

 from clay to marl deposit, its explanation is sought 

 in a change from salt water of the first lake period to 

 fresh water in the second, for which a theoretic ex- 

 planation is given; but the evidence for this is not 

 considered final. From a critical study of the super- 

 position of many shore terraces (see the plate oppo- 

 site), it is shown that the first lake did not rise high 

 enough to reach an overflow outlet; that the greater 

 number of terraces now visible were formed during 

 halts in the rise of the second great lake; that the 

 highest or Bonneville terrace, nine hundred or more 

 feet above the present Great Salt Lake, marks a stand 

 at the level of overflow northward to Snake Eiver; 

 that the next most pronounced terrace, known as 

 the Provo, four hundred feet lower, marks a halt 

 in the drainage of the waters when the outlet had 

 been cut down through softer rocks to a hard lime- 

 stone sill. The reduction of the lake-surface to a still 

 lower level, as in the present shallow sheet of water, 

 has been effected entirely by climatic change, by 

 which the ratio of precipitation to evaporation has 

 been decreased. When at its highest level, Lake 

 Bonneville was three hundred miles long between 

 latitudes 37° 40' and 42° 20', and one hundred and 

 seventy miles broad between the meridians 111° 3.5' 

 and 114° 1.5' of west longitude. Its shore-line was 

 very irregular, advancing around broken promonto- 

 ries, and retreating into fiord-like bays. Numerous 

 islands stood above its broad, deep, fresh waters, and 

 from Its sliores the enclosing mountains rose five to 

 eight thousand feet. Now it is represented by a mere 

 film of brine on the borders of a desert plain. Pre- 

 vious to the rise of the first lake, the base-level of the 

 basin drainage was low for a long period, as is proved 

 by the distinct overlap of tlie lacustrine deposits on the 

 eroded mountain-slopes, as shown in the second plate 

 here copied on p. 573, or on the alluvial cones built 



by old streams flowing from the mountain valleys; 

 but the conclusion tliat this long period liad a dry 

 climate is not fully proved. For 'if, as is mentioned 

 below, a considerable tilting has already deformed 

 the recently made Bonneville terrace, one may fairly 

 suppose a much greater distortion in the long time 

 since the 'beginning of the first lake; and this distor- 

 tion may have been sufiiclent to raise a barrier behind 

 which the lake-waters accumulated. The change 

 from the prelacustrine condition would then have 

 been orographic rather than climatic. The relation 

 of the glaciatlon of the neighboring ranges to the 

 lakes is not shown directly, although three old mo- 

 raines are found within the terrace limits; for none 

 of these give good opportunity for observation, and 

 the one at the mouth of Little Cottonwood canon is 

 so dislocated by recent faulting thai its attitude with 

 relation to the terraqes cannot be deciphered. Ke- 

 cent discoveries by Mr. I. C. Russell in the western 

 part of the Great Basin may throw further light on 

 this question. Volcanic eruption took place in the 

 basin during the disappearance of Lake Bonneville; 

 and both the Bonneville and -Provo terraces have 

 been warped from their originally level plains, and 

 by different amounts. From measures taken along 

 the eastern shore-lines, lines of equal deformation 

 aie constructed; and these show very clearly a rela- 

 tive elevation of the centre, or south-western part, of 

 the old lake-bottom of as much as three hundred feet 

 since the Bonneville terrace was made, and a hundred 

 and twenty-six since the Provo. This tilting ac- 

 counts for the eccentric position of the present shal- 

 low lake-remnant at the north-eastern margin of its 

 flat desert. A fault of flfty to seventy-five feet has 

 been made along the foot of the Wahsatch i-ange, be- 

 tween Willard and Levan, since the lake lost its out- 

 let. The author therefore concludes that volcanic 

 activity and mountain growth have not yet ceased 

 in this neighborhood. 



Special interest is attached to this investigation, as 

 it is the first detailed study of an example of those 

 great interior lakes so numerous at a comparatively 

 recent period of the earth's history, and now so great- 

 ly reduced in area, or even converted into saline or 

 sandy deserts. The largest of these was probably the 

 one that united the Aral and the Caspian; another 

 vast interior sea occupied much of what is now the 

 desert of Gobi; and smaller examples could be named 

 in the Argentine Republic and in northern Mexico. 

 Central Africa, lying within the belt of heavy equa- 

 torial rains, still preserves a climate moist enough to 

 fill its lakes to overfloii'ing ; but the recent di-ying-up 

 of the outlet of Tanganyika shows that the change so 

 distinct elsewhere is beginning to make itself felt 

 even there. It will be long before any of these other 

 great basins is known as well as that one so care- 

 fully studied by our government surveyors. 



W. M. Davis. 



CHEMICAL AND PHYSIOLOGICAL RE- 

 SEARCHES ON THE PTOMAINES. 



During the last few years much attention has 

 been directed to the study of the chemical nature 

 and physiological action of the so-called post-mortem 

 alkaloids (or ptomaines). These mysterious bodies, 

 which are apparently formed in such small quanti- 

 ties as to make their detection and separation an ex- 

 tremely diflScult operation, were originally regarded 

 by both Selmii and Schwanert- (1874) as exclusively 



1 Abstract in Berichte deutxch. chem. ffesflhc/i., vi. 142. 

 - Bericlite dentKli. chem. gesetlsc/i , v'ii. 1332. 



