542 General Notes. [July, 
drifting sand, and the black glaze is produced by the action of the 
ot sun on the oxide of iron, which must be partially reduced to 
the metallic state. The heat of the sun on the rocks on this mesa 
will reach fully 150° F.‘for some months, each year, and must 
produce a powerful effect on the physical character of the rocks. 
Indeed I am satisfied that if our sedimentary rocks were subjected 
to strong solar heat and moisture for a period of time, they would 
be completely metamorphosed. The mesas in this part of Pima 
county, range from 2000 to 3000 feet above sea level, and the 
highest mountains are from 8000 to gooo feet above the sea. The 
timber on the mesas is locally mesquite, cats’ claws (a species of 
mesquite) and palo verde, and a shrub called by the Mexicans 
Edonella. At an elevation of 4000 to 5000 feet, we find scrub 
oak, and 7000 to 8000 feet pine. These elevated regions come 
within the range of prevalent dew falls. While on the mesas dew 
is seldom or never seen 
GEOGRAPHY AND TRAVELS.! 
THE VOYAGES OF THE WILLEM BARENTS AND THE ISBJORN IN 
THE Barents SeA.—The year 1879 will always be memorable in 
the record of Arctic exploration for the discovery of the Northeast 
passage by Nordenskiold, of whose successful voyage accounts 
have been given in former numbers of the Naturauist. He has 
now returned to Europe and been received with great honors at 
the various cities he has visited on his way to his northern home. 
Other less important but still remarkable voyages into the Arc- 
tic seas were also made during the last summer. : 
n the NaruraList for November, 1879, we noticed the sailing 
of the Dutch North Polar Expedition in the schooner Willem Ba- 
rents, and of Capt. A. H. Markham in the yacht Zsġjorn. Both 
having returned, an interesting account of their voyages prepared 
Capt. Markham has been read before the Royal Geographical 
Society? 
The Willem Barents found the edge of the pack ice on July 5; 
in lat. 75° 30’ N., long. 26° E. After stopping at Vardo, the ex- 
of Novaya Zemlya, soon separating not to meet again. The Wil- 
lem Barents, after placing a memorial stone at Cape Nassau, took 
a northward course unobstructed by ice on the 54th meridian, 
and on September 7th they sighted high land, supposed to be 
ount Beunn on MacClintock’s island, Franz Josef Land, distant 
about sixteen miles. A broad belt surrounded the land, and the 
weather being threatening they turned back and arrived safely at 
Hammerfest on September 24th. 
1 Edited by ELLIS H. YARNALL, Philadelphia. 
? Proceedings of the Royal Geographical Society, January, 1880. 
