Sulphur deposits of the Valle de la Coipa situated at about 90 or 100 miles east North east from Copiapo

To go to the valle de la coipa you leave Copiapo early in the morning travel up the river till you arrive at a small farm with a vineyard called Punta negra where you meet with a ravine of considerable size called Despoblado. you travel up that ravine in nearly a northerly direction till you arrive to a spot called Puquios, near copper mines, where you find water and pasturage. you pass there the first night. the 2^d day you continue your journey up the ravine till you arrive at the ravine or quebrada called Sant-Andres which you enter by a road on the slope of the hill. you find in Sant-Andres water and pasturage to pass the 2d night. the third day you travel up the ravine of S^t Andres following a North-east direction till you arrive at the ravine or quebrada de la Coipa till you meet a small rill rendered brackish by sulfate of alluminaQQQQ and iron. ascending the ravine you come to a spot where it widens and where grass and water are again to be found. This place is remarkable for a chasm of red clay cut by thin veins of gypsum and by a great number of blocks of granite between which live many viscachasQQQQ. You here pass the 3^d night— The following day you descend the banks of the rill for about for about a mile retracing your route of the former day for about a mile when you come to a ravine lying towards the east. You travel upwards in that dry ravine for about 3 miles where it ends. and on the summit of the hill which forms its boundary you find large superficial beds of sulphur mixed with sulphate of alumina and a white stony matter the nature of which I do not remember. You find in the ravines of the vicinity pumice, lavas, calcinée granite & porphyry & other volcanic productions.

The formation of all the country from Sant Andres is generally of granite and Porphyry covered by volcanic eruptions. The volcanic eruptions present generally a red appearance whilst the granite & porphyry formation on which they lay is black. there are many spots where you can see the points of the granitic hills rise in the middle of the volcanic formations the lava being not in sufficient quantity to cover the whole. All the ravines have been formed after the eruptions of Lava. This volcanic formation extends from Copiapo to Atacama forming in some places regular basaltique elevated plains which retain the waters of the western side of the Cordilleras and cause those salted Lagunes where the inhabitants of Copiapo, attacamaQQQQ &c provide themselves with that article.

[The paragraphs above are Charles San Lambert’s memorandum. The paragraph below is CD’s extract (DAR 37: 648) and the CD note is taken from DAR 37: 648 too.]

You travel upwards in that dry ravine [Santandrés] for about 3 miles, where it ends, & on the summit of the hill which forms its boundary, you find large superficial beds of Sulphur & the Sulphate of Alumina.— In the ravine there are scattered about fragments of Pumice Lavas calcinèe Granite & Porphyry & other Volcanic productions.— The formation of all the country from Sant Andrès is generally of Granite & Porphyry covered by Volcanic eruptions. These substances present generally a red appearance, whilst the Granite & Porphyry formation on which they lay is black.— There are many points, where you can see the points of the Granitic hills rise in the middle of the Volcanic formation; the Lava not being in sufficient quantity to cover the whole.— All the ravines have been formed after the eruptions of the Lava.— This Volcanic formation extends from Copiapò to Atacama, forming in some places regular basaltic elevated plains. These detain the waters which flow from the Western side of the Cordilleras & cause those Salt lakes, where the inhabitants of Copiapò & Atacama provide themselves with that article.