118 research outputs found
Remote sensing studies and morphotectonic investigations in an arid rift setting, Baja California, Mexico
The Gulf of California and its surrounding land areas provide a classic example
of recently rifted continental lithosphere. The recent tectonic history of eastern Baja
California has been dominated by oblique rifting that began at ~12 Ma. Thus,
extensional tectonics, bedrock lithology, long-term climatic changes, and evolving
surface processes have controlled the tectono-geomorphological evolution of the eastern
part of the peninsula since that time. In this study, digital elevation data from the Shuttle
Radar Topography Mission (SRTM) from Baja California were corrected and enhanced
by replacing artifacts with real values that were derived using a series of geostatistical
techniques. The next step was to generate accurate thematic geologic maps with high
resolution (15-m) for the entire eastern coast of Baja California. The main approach that
we used to clearly represent all the lithological units in the investigated area was objectoriented
classification based on fuzzy logic theory. The area of study was divided into
twenty-two blocks; each was classified independently on the basis of its own defined
membership function. Overall accuracies were 89.6 %, indicating that this approach was
highly recommended over the most conventional classification techniques. The third step of this study was to assess the factors that affected the
geomorphologic development along the eastern side of Baja California, where thirty-four
drainage basins were extracted from a 15-m-resolution absolute digital elevation model
(DEM). Thirty morphometric parameters were extracted; these parameters were then
reduced using principal component analysis (PCA). Cluster analysis classification
defined four major groups of basins. We extracted stream length-gradient indices, which
highlight the differential rock uplift that has occurred along fault escarpments bounding
the basins. Also, steepness and concavity indices were extracted for bedrock channels
within the thirty-four drainage basins.
The results were highly correlated with stream length-gradient indices for each
basin. Nine basins, exhibiting steepness index values greater than 0.07, indicated a
strong tectonic signature and possible higher uplift rates in these basins. Further, our
results indicated that drainage basins in the eastern rift province of Baja California could
be classified according to the dominant geomorphologic controlling factors (i.e., faultcontrolled,
lithology-controlled, or hybrid basins)
Conservation genetics of the Loggerhead sea turtle, Caretta caretta, from the central Mediterranean : an insight into the species’ reproductive behaviour in Maltese waters
Loggerhead sea turtle, Caretta caretta (Linnaeus, 1758), nestlings were investigated through
specimens found dead either after hatching or unhatched (n = 120) from eight nests around the
Maltese islands (Central Mediterranean). Molecular genetics was used to conduct maternity and
paternity tests of the collected specimens utilizing expanded mitochondrial DNA sequences from the
control region (858 bp) and 25 microsatellite loci (12 dinucleotide loci and 13 tetranucleotide
loci). Mitochondrial data produced two haplotypes, CC-A2.1 and CC-A3.1, with the most common
haplotype being present in seven nests. Microsatellite data revealed the identity of six different
females that were involved in the deposition of the eggs in the eight turtle nests analysed. This
confirms that two females laid multiple nests. Additionally, microsatellite data allowed for the
determination of multiple paternity, with one clutch being sired by two fathers. These
results are useful for monitoring the genetic diversity of loggerhead sea turtle nestlings and of
the turtle mothers and fathers contributing to future turtle offspring, which rely on Maltese sandy
beaches for their successful start to life. Effective conservation management benefits from merging
scientific knowledge with effective measures at potential nesting sites to avoid losses of
nestlings caused by
human negligence.peer-reviewe
3D Recording and Interpretation for Maritime Archaeology
This open access peer-reviewed volume was inspired by the UNESCO UNITWIN Network for Underwater Archaeology International Workshop held at Flinders University, Adelaide, Australia in November 2016. Content is based on, but not limited to, the work presented at the workshop which was dedicated to 3D recording and interpretation for maritime archaeology. The volume consists of contributions from leading international experts as well as up-and-coming early career researchers from around the globe. The content of the book includes recording and analysis of maritime archaeology through emerging technologies, including both practical and theoretical contributions. Topics include photogrammetric recording, laser scanning, marine geophysical 3D survey techniques, virtual reality, 3D modelling and reconstruction, data integration and Geographic Information Systems. The principal incentive for this publication is the ongoing rapid shift in the methodologies of maritime archaeology within recent years and a marked increase in the use of 3D and digital approaches. This convergence of digital technologies such as underwater photography and photogrammetry, 3D sonar, 3D virtual reality, and 3D printing has highlighted a pressing need for these new methodologies to be considered together, both in terms of defining the state-of-the-art and for consideration of future directions. As a scholarly publication, the audience for the book includes students and researchers, as well as professionals working in various aspects of archaeology, heritage management, education, museums, and public policy. It will be of special interest to those working in the field of coastal cultural resource management and underwater archaeology but will also be of broader interest to anyone interested in archaeology and to those in other disciplines who are now engaging with 3D recording and visualization
Remote sensing studies and morphotectonic investigations in an arid rift setting, Baja California, Mexico
The Gulf of California and its surrounding land areas provide a classic example
of recently rifted continental lithosphere. The recent tectonic history of eastern Baja
California has been dominated by oblique rifting that began at ~12 Ma. Thus,
extensional tectonics, bedrock lithology, long-term climatic changes, and evolving
surface processes have controlled the tectono-geomorphological evolution of the eastern
part of the peninsula since that time. In this study, digital elevation data from the Shuttle
Radar Topography Mission (SRTM) from Baja California were corrected and enhanced
by replacing artifacts with real values that were derived using a series of geostatistical
techniques. The next step was to generate accurate thematic geologic maps with high
resolution (15-m) for the entire eastern coast of Baja California. The main approach that
we used to clearly represent all the lithological units in the investigated area was objectoriented
classification based on fuzzy logic theory. The area of study was divided into
twenty-two blocks; each was classified independently on the basis of its own defined
membership function. Overall accuracies were 89.6 %, indicating that this approach was
highly recommended over the most conventional classification techniques. The third step of this study was to assess the factors that affected the
geomorphologic development along the eastern side of Baja California, where thirty-four
drainage basins were extracted from a 15-m-resolution absolute digital elevation model
(DEM). Thirty morphometric parameters were extracted; these parameters were then
reduced using principal component analysis (PCA). Cluster analysis classification
defined four major groups of basins. We extracted stream length-gradient indices, which
highlight the differential rock uplift that has occurred along fault escarpments bounding
the basins. Also, steepness and concavity indices were extracted for bedrock channels
within the thirty-four drainage basins.
The results were highly correlated with stream length-gradient indices for each
basin. Nine basins, exhibiting steepness index values greater than 0.07, indicated a
strong tectonic signature and possible higher uplift rates in these basins. Further, our
results indicated that drainage basins in the eastern rift province of Baja California could
be classified according to the dominant geomorphologic controlling factors (i.e., faultcontrolled,
lithology-controlled, or hybrid basins)
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