*3.3. Example 3: Wetar Island (Indonesia; Banda Sea)*

The locality corresponds to the Banda Sea coast of the Wetar Island in eastern Indonesia (Figure 1). There, Cenozoic volcanic, volcaniclastic, and reefal carbonate deposits crop out [69]. Presumably, their destruction by wave abrasion and weathering leads to megaclast creation; it cannot be excluded that some megaclasts were formed as a result of slope collapse and subsequent downslope

transport. This means that the origin of this new locality can be highly complex, but the role of abrasion seems to be leading.

On the eastern plot, blocks with the maximum size of up to 10 m (the prevailing size was 3–5 m) occurred sporadically (Figure 6). These lay either individually or in small groups. The biggest stones were angular. The deposit package density was very low with regard to the distance between megaclasts (even when these occur in groups). These coastal megaclast deposits were restricted to the very shoreline. On the northeastern plot, the number of megaclasts was bigger (Figure 7). These were chiefly blocks of different size (commonly < 5 m), but there were also megablocks, the biggest of which reached 20 m in size. The particle angularity was well visible. The package density was moderate (even high in some places), but the deposits also occurred like a narrow ribbon along the shoreline. On the both plots, clasts >3 m in size were distinguished easily; the satellite image evidence is enough to confirm the presence of true coastal megaclast deposits. The resolution of the images permitted us to distinguish blocks from megablocks; boulders were not seen at all (it was unclear whether these exist). A different package density was visible without any difficulty. Size and shape of individual particles can be registered when their size exceeds 5 m. Better to say, these can be examined chiefly for large blocks and all megablocks. Dense vegetation cover of the island and, particularly, along the shoreline 'masks' the coastal megaclast deposits, but this does not preclude for megaclast accumulation tracing over the studied plots. The position and the orientation of megaclasts do not suggest against their resedimentation, and, if so, it cannot be excluded that high-energy events contributed to motion and destruction of these stones.

**Figure 6.** The eastern plot of the Wetar Island locality (the view provided by the Google Earth Engine).

Coastal megaclasts have been reported earlier from many localities of Southeast Asia, including those of China, Taiwan, Thailand, Malaysia, Indonesia, and the Philippines [70–94]. Strong influences of tsunamis [95,96] and super-typhoons [97] contribute to the formation of such deposits. However, all this evidence has been obtained outside eastern Indonesia and chiefly on coasts open to either the Indian or Pacific Oceans. The Wetar Island locality sheds light on the coastal megaclast deposits formed in a distinct geographical setting, namely on the coast of a relatively small, intra-island sea, which makes addition to the regional knowledge of such deposits. Therefore, the Google Earth Engine permits extension of the available knowledge of megaclast occurrence in Southeast Asia.

**Figure 7.** The northeastern plot of the Wetar Island locality (the view provided by the Google Earth Engine).

#### *3.4. Example 4: Humboldt o Coredo Bay (Colombia*/*Panama; Eastern Pacific)*

The locality corresponds to the Humdoldt o Coredo Bay and its vicinities. It is situated on the Pacific coast of Central America, exactly at the border between Colombia and Panama, north of Jurado (Figure 1) where the Cretaceous-Eocene basement and volcanic arc complex dominate the local geological setting [98]. Wave destruction and weathering of hard parent rocks contributes to formation of multiple megaclasts. Apparently, abrasion is chiefly responsible for the origin of these deposits.

On the southern plot, small and medium blocks (typical size is <5 m) formed lenticular deposits around a small bay (Figure 8). The biggest particles were angular, but the shape of the majority of particles could not be recognized at the available resolution. The width of the ribbon of deposits differed, as well as their package density. A few huge blocks (but these did not reach the size of megablocks) lay individually in the central part of the plot. Generally, it is possible to record the deposits heterogeneity. On the northern plot, the coastal megaclast deposits were very similar to those described on the southern plot, with two exceptions: the mean size of blocks was bigger, and there were a few megablocks (up to 20 m in size or even more; Figure 9). On both plots, clasts >3 m in size were distinguished easily, and the presence of true coastal megaclast deposits was evident. The resolution of satellite images permitted us to distinguish blocks from megablocks; boulders were not seen at all, although these, presumably, exist. A different package density was visible without any difficulty. The size and shape of individual particles can be registered when their size exceeds 5 m (large blocks and megablocks). The difficulties were linked, first, to the 'masking' effect of the vegetation cover and, second, uncertainty with some features on the northern plot that could be either megaclasts or parent rock exposures (or semi-detached megaclasts). Presumably, the both difficulties will remain even in the case of a much higher resolution of satellite images. The spatial position and orientation of stones permitted us to hypothesize the absence of significant reworking, i.e., these seemed to be primary, undisturbed coastal megaclast deposits.

Previous megaclast studies on the Pacific coast of the Americas are scarce, and, particularly, focused on two geographical domains, namely the Baja California Peninsula in Mexico [4,5] and northern and central Chile [41,99,100]. If so, the information from the Humboldt o Coredo Bay locality fills significant gap in the regional knowledge of coastal megaclast deposits characterizing those of Central America. Finding this locality with the Google Earth Engine implies the existence of coastal megaclast deposits on the Pacific coast of Central America (probably, for the first time).

**Figure 8.** The southern plot of the Humboldt o Coredo Bay locality (the view provided by the Google Earth Engine).

**Figure 9.** The northern plot of the Humboldt o Coredo Bay locality (the view provided by the Google Earth Engine).
