GEOLOGY AND PALEONTOLOGY OF CANAL ZONE


road tunnel north of Miraflores Locks (Woodring and Thompson, 1949, p. 241), but it probably is submerged by Miraflores Lake. Cole has recently described thin sections of specimens from the type lot (Cole, 1953a). He also identified and described Lepidocyclina parvula, also a lepidocycline species, and Miogypsina panamensis from locality 131a, MacDonald's locality near Red Tank.
 Corals.-MacDonald found two species of corals in limestone at his locality near Red Tank (locality 131). Both were recorded by Vaughan from the Emperador limestone member of the Culebra formation and one from the Anguilla formation (Vaughan, 1919a, p. 209; Geological Survey locality 6256). The following corals, found in limestone at the base of the La Boca member at localities 123 and 129, were identified by J. W. Wells:

 Corals from limestone at base of La Boca marine member of Panamd formation


 [Identification by J. W. Wells]

Stylophora imperatoris Vaughan- _ -Stylophora macdonaldi Vaughan ------- ------_---Acropora saludensis Vaughan ..------ __Porites cf. P. douvillei Vaughan - -_------- _-Montastrea imperatoris Vaughan ------Montastrea costata (Duncan)------------


Localities
123 129
-- X
-- X

X X


 According to Wells, all except one of the above species (or comparable species) occur in the Emperador limestone member of the Culebra formation and that species (Montastrea costata) occurs in the Culebra formation proper. Two are found in the Antigua formation and three in the Anguilla formation of the Leeward Islands.
 Mollusks.-Though mollusks are widespread in the La Boca member, they are nowhere abundant and most of them are not well preserved. Crepidula sp. (locality 125), Neverita? sp. (locality 130), and Turritella cf. T. collazica (locality 123) are the only species in the families covered by chapter A of the present report.
 Echinoids.-Limestone at the base of the La Boca member at locality 123 yielded an echinoid identified by C. W. Cooke as Clypeaster concavus?. That species occurs in the Caimito formation of the Rio Mandinga area and in both the Antigua and Anguilla formations of the Leeward Islands. According to Jackson, Clypeaster gatuni, a Gatun species, was found in limestone in a swamp north of Ancon Hill (Jackson, 1917, p. 491). The swamp is now filled, but limestone occuring in that region presumably is in the La Boca marine member.
 Age.-The Panama formation was the first formation in or near the Canal Zone to be given an age assignment. Wagner thought that reddish conglomerate and fragmental rocks at Panama are Permian (Wagner, 1861, p. 6, 16). Though that opinion, of course, has not


been taken seriously, Hill was inclined to consider the formation pre-Tertiary (Hill, 1898, p. 202). Bertrand and Zircher (1899, p. 90-91), however, pointed outA that the tuff on the Pacific slope of the district to be traversed by the canal is younger than strata ("gres ligniteux") now referred to the Culebra formation, and Howe (1907, p. 117) came to the same conclusion.
 Though the La Boca fossils and the Culebra fossils for the most part indicate somewhat different facies, they have essentially the same age significance: both have Oligocene and Miocene affinities. The La Boca member-and presumably the entire Panami formation-is not much younger than the Culebra formation. Like the Culebra formation, it is considered early Miocene. The entire succession above the Las Cascadas agglomerate (Culebra, Cucaracha, and Panama' formations) is thought to represent the early half of early Miocene time; that is, the disputed Oligocene or Miocene. If the Panami formation east of the Canal Zone does not include the equivalent of the Culebra formation, presumably there is a slight discontinuity between the Caimito and Panami formations east of the Zone.
 GATUN FORMATION
 The two remaining Tertiary formations to be described are found in the Gatun Lake and Caribbean coastal districts. The older of the two is the Gatun formation, well-known for its rich fauna. In fact, the fossils of the Gatun formation attracted attention at' an early date. When Blake traveled across Panama. in 1853 on his way to California to join one of the transcontinental railroad surveying parties, he collected a few Gatun fossils (Blake, 1857, p. 1). Two years later Newberry crossed Panama on the same mission and also collected some Gatun fossils, but left' no account of his observations. At about the same time another traveler briefly commented on fossils at Monkey Hill (now known as Mount Hope) but saw none at Gatun (Deck, 1855, p. 241). A search of books and magazine articles written by Californiabound travelers during and after the gold rush doubtless would reveal other accounts.
 The Gatun formation was named by Howe (1907, p. 113-114). In Spanish orthography the name is Gatd'n. That name, however, was not the earliest for the formation. Hill had already used the names Monkey Hill formation and Mindi Hill beds (1898, p. 176, 180). Howe, indeed, used both Gatun formation and Monkey Hill formation in a structure section in the publication in which he proposed his name (1907, pl. 147), and in a later publication used only Monkey Hill formation (1908, p. 228). MacDonald's usage apparently established preference for Howe's name (MacDonald, 1913, p. 530). The type area is


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