■Geology and Mineralogy. 69 



motion was found when the shot used were small, about a quarter 

 of an inch in diameter. The observations in the pit apparently 

 indicate that an earthquake's motion at a distance from its origin 

 is practically superficial and that a building whose foundations 

 rose freely from hard ground at the bottom of a trench, ought to 

 feel but little movement ; but these inferences need to be tested 

 by further experiment. 



The writer has also received a little lOmo. pamphlet of twenty- 

 three pages " On the causes of Earthquakes," which is a reprint 

 from the columns of the Japan Mail of the shorthand report of a 

 popular lecture delivered in Tokio by Professor Milne on October 

 16, 1880. In the reprint the original columns of the newspaper 

 have been curiously transposed, so that to get the lecture in 

 proper order the pages of the pamphlet must be taken thus: 1-7, 

 14-20, 7-14, 20-23. The exact line of separation on pages 7, 14 

 and 20, will be evident to the reader. c. G. k., jr. 



2. On Submarine Valleys on the Pacific Coast of the United 

 States; by George Davidson. (Bulletin California Acad. Sci., 

 ii, 265, January, 1887.) Off the Pacific Coast south of Cape Men- 

 docino, the distance to the 100-fathom line is generally about 

 ten miles ; there is then a sharp descent to 500 or 600 fathoms, 

 and from this a decline to 2000 to 2400 fathoms within 40 or 5 

 miles. Within the marginal plateau bounded by the 100-fathom 

 curve, the soundings of the coast survey have found several deep 

 valleys. Mr. Davidson reported to the California Academy, in a 

 former paper, the existence of one of those remarkable valleys in 

 Monterey Bay, leading toward the lowlands at the great bend of 

 the Salinas River; another off Point Huaneme at the eastern 

 entrance to the Santa Barbara Channel, heading toward the 'open- 

 ing of the Santa Clara valley; one or two at the mouth of the 

 Laguna Mugu; two or three off the southern point of Carmel 

 Bay, the deepest of which goes far into the bay. 



As more recent discoveries, he mentions three valleys off the 

 coast south of Cape Mendocino. One is off Point Delgada at 

 Shelter Cone; it cuts through the marginal plateau in a direction 

 toward the culminating point in the mountain's of the coast, a 

 peak 4236 feet high. The 100-fathom line is six miles off Point 

 Delgada; but in its course where crossed by the valley the depth 

 reaches 400 fathoms; and a depth of 100 fathoms is within one 

 and a quarter miles of the shore, while 25 fathoms is near the 

 shore cliffs. 



A few miles farther north a second submarine valley comes in 

 from the west-southwest, reaching toward the coast three miles 

 north of Point of Gorda and less than a mile north of the mouth 

 of the Mattole River. At the head of this steep-sided valley 

 there is a depth of 30 fathoms one-third of a mile from the shore, 

 and of 100 fathoms one-third of a mile outside of this; and at the 

 edge of the 100-fathom plateau, here six miles from Point Gorda, 

 the depth is 520 fathoms. It is remarkable that the barrier of 

 coast-line at the head of this valley is over 2000 feet high. 



