440 



THE BOLSON DE MAPIMI. 



There is a singular geological formation in the northern part of 

 Mexico, lying on the road between the cities of Chihuahua and Mon- 

 terey, and extending northwardly from the towns and haciendas of 

 Mapimi, San Juan, San Lorenzo and San Sebastian towards the 

 Rio Grande, called the Bolson de Mapimi, or Pouch of Mapimi. 

 Leaving Mapimi, the road continues about three miles to the eastern 

 mountain chain, and then winding nearly two miles through a canon, 

 or gorge, it leads to a very open level valley, which is the com- 

 mencement of the Bolson. Towards the right of the road, east- 

 wardly, at the distance of from three to five miles, a steep, high 

 mountain chain of limestone, rises precipitously, while another 

 chain towers up to the left, at the distance of about twelve miles. 

 Both chains gradually diverge, but especially the eastern arm, which 

 stretches north-eastwardly and then bends to the south-west, at an 

 angle, leaving a deep cut de sac or depression in the middle from 

 which the country has probably derived its name. All around is an 

 immense chapparal plain, while in the distance the Rio Nasas runs 

 towards the north into the immense basin, and forms the large Laguna 

 de Tlagualila, usually set down on maps and mentioned in geographi- 

 cal works as Lake Cayman. The Nasas is said by Dr. Wislizenius 

 to be the Nile of the Bolson. Coming about 150 leagues from the 

 western part of Durango, from the Sianori mountains, it runs north- 

 westwardly and northerly towards this Pouch, and the wide and 

 level country along the river is yearly inundated by the floods, and 

 owes its fertility to this circumstance. The limits of the Bolson de 

 Mapimi have never been clearly defined either geographically or 

 politically for its immense wilderness has been neither fully explored 

 or occupied in consequence of the danger of encountering the rob- 

 ber hordes by whom its recesses are infested. The northern portion 

 is supposed to belong to the State of Chihuahua, and the southern 

 to Durango. Nor are its general physical properties clearly known, 

 though the common and perhaps erroneous impression in the coun- 

 try is that it is a low, flat, swampy country and a mere desert. The 

 two terminating points of Dr. Wislizenius's transit through the 

 Bolson are Mapimi, where he entered it, and El Paso, or a point 

 between Paso and Parras, where he left it. At Mapimi, the eleva- 

 tion above the sea was 4,487 feet; in the valley of the Nasas, at 

 San Sebastian, 3,785; at San Lorenzo, 3,815; at San Juan, 3,775; 

 and towards the eastern edge of the Bolson, at El Paso, 3,990, 

 and at Parras, 4,987. We perceive, therefore, that the valley of 

 of the Nasas, which may be called the vein and centre of the Bol- 

 son has a mean elevation of 3,800 feet; and though from 500 to 



