span>, <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="st">"Fine_gravel"</span>, <span class="st">"Coarse_gravel"</span>, <span class="st">"Sand_1_2_mm"</span>, <span class="st">"Mud"</span>, </span>
<span>            <span class="st">"Cobbles_64_257_mm"</span>, <span class="st">"Boulders_257_mm"</span>, <span class="st">"Bedrock"</span>, <span class="st">"Gravel_3_64_mm"</span>,</span>
<span>            <span class="st">"Mud_S