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The building is circular in form, some 450 feet in diameter of the base and its latest construction on the top platform attained an elevation of about 100 feet. The sides rise in sloping walls that have an inclination of 45o. These walls are broken by three terraces respectively 13, 38, and 68 feet wide, while the top platform has a diameter of 130 feet. The sloping wall to be the first terrace measures 46 feet, that to the second 24, while that to the third sems to rise only 4 feet. The top platform of fourth terrace rises 5 feet higher. This top platform and the terrace below (68 feet wide) are covered with volcanic material to the depth of 7 feet on the platform and 12 feet on the terrace. On the southern-western side of the platform made by leveling off this volcanic material was a mound of earth and ashes mingled with chunks of lava and water-worn boulders that rose some 20 feet higher. On the lower terraces wherever there was lodging space and about the base of the structure is found volcanic material similar to that encountered covering the two top terraces. At one place o the eastern side it had accumulated to a depth of 17 ½ feet and held the lava back 33 feet from the pyramid. At another point the ruins of a lofty platform extend out from the pyramid 29 feet, and 11 feet of this lies under the lava of the Pedregal. Whenever we have excavated to the pavement surrounding the temple, the story is the same first a mass of lava shells, then a thick stratum of volcanic material consisting of yellowish clay, ashes and fine pumice, above that the blackened stratum caused by the great heat at the time of the Pedregral lava flow and resting upon that a thick accumulation of recent soil. Where the volcanic material had slid down off the slopes and accumulated at the base of the cone, the lava flowed in over it, burying the base far beneath the enveloping mass.

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